Easy data structure and algorithm practice puzzle.
Given [subtotal, taxPercent], return the total with tax, rounded to a whole number. Add subtotal x taxPercent / 100 to the subtotal. Real checkout systems do this in whole cents, not decimals, because 0.1 + 0.2 doesn't come out to exactly 0.3 on a computer.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Order Sampler, a pipeline you can run and download. See every Software Engineer project.
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