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Coding AI

Code, formulas and queries you can read, run and trust, from scripts to spreadsheets. 151 exercises, about 5 minutes each.

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• Add a cron line that matches the others in a crontabProduct managers · Showing an example of what you wantPremium
• Add dark mode by overriding your existing CSS variablesSoftware developers · Setting limits and rulesPremium
• Add input checks to your number guessing gameHigh school students · Setting limits and rulesPremium
• Add input validation to a Java method with exact messagesSoftware developers · Giving the right contextPremium
• Add labels to a signup form without rewriting the pageHigh school students · Setting limits and rulesPremium
• Add mail-merge greetings for couples and missing namesNonprofit staff · Showing an example of what you wantPremium
• Add type hints that still run on Python 3.8Software developers · Giving the right contextPremium
• Assign donor tiers from this fiscal year's giftsNonprofit staff · Giving the right contextPremium
• Bucket unpaid invoices by days past dueFinance and accounting · Setting limits and rulesPremium
• Build a JSON payload in the exact shape an API wantsMarketing and content · Asking for a format you can usePremium
• Build a running balance where debits mean money outFinance and accounting · Giving the right contextPremium
• Build a saved reply with placeholders the helpdesk supportsCustomer support teams · Keeping the AI to your sourcesPremium
• Build a shipping label request with converted unitsSmall business owners · Keeping the AI to your sourcesPremium
• Build new hires' work emails from their namesHR and recruiting · Showing an example of what you wantPremium
• Build tagged campaign links with one sheet formulaMarketing and content · Asking for a format you can usePremium
• Calculate an agent's take with a capped broker splitReal estate agents · Giving the right contextPremium
• Calculate attendance rates the way your school countsTeachers · Giving the right contextPremium
• Catch the join bug in a churn query before it shipsProduct managers · Catching mistakes and made-up factsPremium
• Center a card in CSS using only what you've learnedHigh school students · Setting limits and rulesPremium
• Check your Big-O answers with exact labelsCollege students · Asking for a format you can usePremium
• Check your program against the assignment before you submitHigh school students · Catching mistakes and made-up factsPremium
• Check your Python translation of AP CSP pseudocodeHigh school students · Catching mistakes and made-up factsPremium
• Clean a UK bank export with plain Python, no pandasFinance and accounting · Setting limits and rulesPremium
• Code an email signature with inline styles onlyMarketing and content · Setting limits and rulesPremium
• Compare A/B conversion, dropping users who saw bothProduct managers · Giving the right contextPremium
• Compute NPS from a survey export with plain PythonProduct managers · Setting limits and rulesPremium
• Convert a Java loop to a stream without losing key orderSoftware developers · Setting limits and rulesPremium
• Convert a promise chain to async/await with three new rulesCollege students · Giving the right contextPremium
• Convert OFFSET paging to keyset paginationSoftware developers · Setting limits and rulesPremium
• Convert two loops to comprehensions on Python 3.7College students · Setting limits and rulesPremium
• Copy approved requests to another tab with Apps ScriptOffice and admin · Setting limits and rulesPremium
• Count an October onboarding funnel in New York timeProduct managers · Giving the right contextPremium
• Count customers by their first-touch channel in SQLMarketing and content · Giving the right contextPremium
• Count headcount by department on a given dateHR and recruiting · Giving the right contextPremium
• Count members per club, including clubs with noneCollege students · Giving the right contextPremium
• Count returns per category without double-counted rowsSoftware developers · Giving the right contextPremium
• Count unique customers in a month with one formulaSmall business owners · Giving the right contextPremium
• Dedupe applicants with pandas, keeping the latest oneHR and recruiting · Giving the right contextPremium
• Draft thank-you emails without sending themNonprofit staff · Setting limits and rulesPremium
• Email yourself a low-stock list with Apps ScriptSmall business owners · Setting limits and rulesPremium
• Explain a background job to your PM without jargonSoftware developers · Saying who it's forPremium
• Explain a regex piece by piece in 5 numbered linesCollege students · Asking for a format you can usePremium
• Explain a room-finder formula to the office managerOffice and admin · Saying who it's forPremium
• Explain a SQL query to an analyst in 4 labeled linesSoftware developers · Saying who it's forPremium
• Explain a SUMPRODUCT formula to a board memberFinance and accounting · Saying who it's forPremium
• Explain an analytics URL filter to a content writerMarketing and content · Saying who it's forPremium
• Explain the Big-O cost of checking a list vs a setCollege students · Asking for a format you can usePremium
• Explain your turtle program to a 10-year-oldHigh school students · Saying who it's forPremium
• Extract a pure function so the fee logic can be testedSoftware developers · Setting limits and rulesPremium
• Find lapsed donors for a win-back appealNonprofit staff · Giving the right contextPremium
• Find out why your text is red, not greenHigh school students · Asking for a format you can usePremium
• Find students above their course average, minus audit seatsCollege students · Giving the right contextPremium
• Find unmatched bank and ledger lines with pandasFinance and accounting · Giving the right contextPremium
• Find why your binary search hangs, without the fixCollege students · Setting limits and rulesPremium
• Finish a practice take-home function without breaking the rulesJob seekers · Setting limits and rulesPremium
• Fix a class average formula that punishes excused workTeachers · Catching mistakes and made-up factsPremium
• Fix a currency lookup that returns wrong ratesFinance and accounting · Catching mistakes and made-up factsPremium
• Fix a KeyError from a stack trace without touching anything elseSoftware developers · Setting limits and rulesPremium
• Fix a shell loop that breaks on filenames with spacesSoftware developers · Setting limits and rulesPremium
• Fix an async forEach without breaking the rate limitSoftware developers · Giving the right contextPremium
• Fix one line that set -e kills, and keep strict modeSoftware developers · Setting limits and rulesPremium
• Flag meta descriptions that run too longMarketing and content · Asking for a format you can usePremium
• Flip "LAST, first" names into clean First LastOffice and admin · Showing an example of what you wantPremium
• Generate hash table practice problems that match your lectureCollege students · Showing an example of what you wantPremium
• Get 3 clues about a buggy average without the answerHigh school students · Setting limits and rulesPremium
• Get clues for a grade function that gives a C for 95High school students · Setting limits and rulesPremium
• Get each ticket's latest status on MySQL 8 without DISTINCT ONSoftware developers · Giving the right contextPremium
• Get hints on an AP CS ArrayList answer without the solutionHigh school students · Setting limits and rulesPremium
• Give a lab partner Glow and Grow feedback on their JavaScriptCollege students · Getting the tone rightPremium
• Keep each student's best quiz attempt with pandasTeachers · Giving the right contextPremium
• Label budget variances as favorable or unfavorableFinance and accounting · Giving the right contextPremium
• Label dates with a July-start fiscal quarterFinance and accounting · Showing an example of what you wantPremium
• List Pro accounts with ticket counts, zeros includedProduct managers · Giving the right contextPremium
• Lock a closed month's tab with a short Apps ScriptFinance and accounting · Setting limits and rulesPremium
• Make a 'what does this print?' quiz on Python dictionariesHigh school students · Keeping the AI to your sourcesPremium
• Make a bake sale table readable for screen readersHigh school students · Setting limits and rulesPremium
• Make a copy of a lab template for every studentTeachers · Setting limits and rulesPremium
• Make JOIN practice questions from a tiny sample databaseCollege students · Showing an example of what you wantPremium
• Make range() practice problems that target off-by-one mistakesHigh school students · Showing an example of what you wantPremium
• Mask card numbers in ticket text before sharingCustomer support teams · Setting limits and rulesPremium
• Measure first-reply time across two time zonesCustomer support teams · Giving the right contextPremium
• Measure week-one retention for a signup cohortProduct managers · Giving the right contextPremium
• Plan a booking automation as short pseudo-code stepsSmall business owners · Asking for a format you can usePremium
• Plan how to split one big diff into 3 commitsCollege students · Asking for a format you can usePremium
• Practice a take-home SQL question on an old MySQLJob seekers · Giving the right contextPremium
• Practice an Excel hiring test with exact rangesJob seekers · Asking for a format you can usePremium
• Preview product photo renames without touching filesSmall business owners · Setting limits and rulesPremium
• Pull company domains from lead emails, flag personal onesMarketing and content · Giving the right contextPremium
• Pull order numbers out of customer messagesSmall business owners · Showing an example of what you wantPremium
• Rank agents by reopen rate without small samplesCustomer support teams · Giving the right contextPremium
• Refactor an if-else chain into a lookup map, plus one new ruleSoftware developers · Setting limits and rulesPremium
• Refactor nested null checks into an Optional chainSoftware developers · Setting limits and rulesPremium
• Replace a racy read-then-write with a single upsertSoftware developers · Giving the right contextPremium
• Replace div soup with semantic landmarks and keep the hooksCollege students · Setting limits and rulesPremium
• Review a migration with one MUST, one SHOULD and one NITSoftware developers · Asking for a format you can usePremium
• Review an Express handler as 4 labeled line commentsSoftware developers · Asking for a format you can usePremium
• See exactly what a mutable default argument doesCollege students · Asking for a format you can usePremium
• See why your substring answer is off by oneHigh school students · Asking for a format you can usePremium
• Set due dates five business days out, skipping holidaysOffice and admin · Giving the right contextPremium
• Shortlist listings for a buyer with pandasReal estate agents · Giving the right contextPremium
• Show employee tenure as years and monthsHR and recruiting · Asking for a format you can usePremium
• Show price per square foot as a ready-to-paste labelReal estate agents · Asking for a format you can usePremium
• Speed up a recursive function with a hand-written memoCollege students · Setting limits and rulesPremium
• Split a tip pool by hours, leaving managers outSmall business owners · Giving the right contextPremium
• Standardize messy phone numbers with one regex formulaOffice and admin · Showing an example of what you wantPremium
• Summarize approved spend by team with one QUERY formulaOffice and admin · Asking for a format you can usePremium
• Total room booking hours by month with SUMIFSOffice and admin · Giving the right contextPremium
• Trace a recursive function one call per lineCollege students · Asking for a format you can usePremium
• Trace a while loop one pass per lineHigh school students · Asking for a format you can usePremium
• Turn a rate-limit spec into a typed TypeScript stubSoftware developers · Setting limits and rulesPremium
• Turn a showings sheet into calendar eventsReal estate agents · Setting limits and rulesPremium
• Turn a UML box into a Java class stub for your teamCollege students · Setting limits and rulesPremium
• Turn curved final percents into letter gradesTeachers · Giving the right contextPremium
• Turn your notes on Python errors into printable flashcardsHigh school students · Keeping the AI to your sourcesPremium
• Understand a NullPointerException in your Java programHigh school students · Asking for a format you can usePremium
• Understand why a loop with setTimeout prints 3, 3, 3College students · Asking for a format you can usePremium
• Update equals and hashCode together for a new ruleSoftware developers · Giving the right contextPremium
• Use the right input types in your field trip formHigh school students · Setting limits and rulesPremium
• Write 3 named JUnit 5 tests with plain assertionsSoftware developers · Setting limits and rulesPremium
• Write 4 unittest boundary tests when pytest isn't allowedCollege students · Setting limits and rulesPremium
• Write a Bash usage message that matches the real defaultsSoftware developers · Keeping the AI to your sourcesPremium
• Write a commit message in your club repo's exact formatCollege students · Asking for a format you can usePremium
• Write a curl call from an API doc for stagingProduct managers · Keeping the AI to your sourcesPremium
• Write a dry-run rename loop for your lab's photo folderCollege students · Setting limits and rulesPremium
• Write a generic TypeScript stub with exact JSDoc linesCollege students · Setting limits and rulesPremium
• Write a Jira search for the bugs that block a releaseProduct managers · Giving the right contextPremium
• Write a LEFT JOIN that keeps customers who spent nothingSoftware developers · Giving the right contextPremium
• Write a NumPy-style docstring that matches what the code doesCollege students · Keeping the AI to your sourcesPremium
• Write a PR description in your team's templateSoftware developers · Asking for a format you can usePremium
• Write a Python log regex with exact group namesSoftware developers · Setting limits and rulesPremium
• Write a README 'How to play' section from your game's codeHigh school students · Keeping the AI to your sourcesPremium
• Write a README config table from the code, not the old docsSoftware developers · Keeping the AI to your sourcesPremium
• Write a rep email lookup that works in Excel 2016Office and admin · Giving the right contextPremium
• Write a revert commit message in your team's formatSoftware developers · Asking for a format you can usePremium
• Write a safe duplicate-cleanup DELETE you can dry-runSoftware developers · Giving the right contextPremium
• Write a sales tax formula that skips wholesale ordersSmall business owners · Giving the right contextPremium
• Write a SKU regex that passes the tests plus a new ruleSoftware developers · Giving the right contextPremium
• Write a SQL query for your club's sign-in appHigh school students · Giving the right contextPremium
• Write a tight VBA macro that hides finished tasksOffice and admin · Setting limits and rulesPremium
• Write a TypeScript type guard without a validation librarySoftware developers · Setting limits and rulesPremium
• Write alt text for a club page, including the decorative imageHigh school students · Giving the right contextPremium
• Write an argparse parser from a CLI spec, and nothing moreSoftware developers · Setting limits and rulesPremium
• Write event schema markup with the corrected dateMarketing and content · Keeping the AI to your sourcesPremium
• Write exactly 3 named Jest tests for a slugify helperSoftware developers · Setting limits and rulesPremium
• Write exactly 5 pytest tests for your team's parserCollege students · Setting limits and rulesPremium
• Write mobile-first CSS for a portfolio project gridJob seekers · Setting limits and rulesPremium
• Write one crontab line that won't overlap or lose logsSoftware developers · Giving the right contextPremium
• Write one production-safe index from an EXPLAIN planSoftware developers · Giving the right contextPremium
• Write SQLite tables from a spec with your team's rulesCollege students · Setting limits and rulesPremium
• Write the HR system update for a promotionHR and recruiting · Keeping the AI to your sourcesPremium
• Write ticket routing rules as clear if/else stepsCustomer support teams · Asking for a format you can usePremium