Arithmetic, against the clock
Questions generated backwards from their answers, so division comes out exact and subtraction never goes negative. Pick your topics, pick a mode, and see what you actually know.
Topics
Nothing here is a test and no score leaves this device. There is no leaderboard to compare against and no claim that speed measures anything but speed.
Nothing leaves this device
Why every question comes out clean
Questions are generated from the answer backwards. For exact division the quotient and divisor are chosen first and the dividend derived, so there is never a remainder. Subtraction picks the result and the amount taken away, so it never goes negative. Percentages pick a whole that makes the answer an integer.
Generating forwards — two random numbers and an operator — is how you get 47 ÷ 6, fractions that will not reduce and percentages with four decimal places. It costs nothing to work backwards and it means a whole session can run without a single awkward question.
The one thing this cannot do is claim curriculum alignment. Levels are described as roughly matching an age range, with a note on what is actually covered, because mapping to a standard means having read that standard and standards differ by country and change.
What the modes are for
60-second sprint measures fluency: how many you can do when there is no time to work anything out longhand. It rewards recall over method.
20 questions removes the clock pressure and measures accuracy instead. The time is still recorded but nothing ends because of it.
Survival ends after three mistakes, which changes how you play — you slow down on the ones you are unsure of, which is usually the more useful habit.
Untimed practice has no ending at all. Useful for working through a topic without any pressure, and the mode to use with a child.
The review is the part that matters
Every session ends with each question you got wrong, alongside what you answered and what it should have been. A score on its own tells you nothing you can act on; a list of the six-times-table questions you missed does.
Related
Worksheet generator for the same questions on paper, and Number Forge for arithmetic as a search problem rather than a speed one.
Questions people actually ask
Does it ever ask something with an ugly answer?
It should not. Questions are built backwards from the answer: exact division picks the quotient and divisor and derives the dividend, subtraction picks the result so it never goes negative, and percentages pick a whole that makes the answer an integer. Generating forwards is what produces 47 ÷ 6.
Can I type a fraction as a decimal?
Yes. 0.5 and 1/2 are compared as exact values rather than as strings, so either is accepted. Division-with-remainder answers accept '6 r 2', '6r2' and '6 remainder 2'.
Is my score sent anywhere?
No. There is no account, no leaderboard and no analytics event carrying anything you did. The session exists in the page and is gone when you close it.
Do the levels match a school curriculum?
They are described as roughly matching an age range, with a note on what each topic actually covers, and deliberately go no further. Claiming alignment to a standard means having read and mapped that standard — and standards differ by country and change.
Why does a wrong answer stay on screen longer?
Because the correct answer is shown with it, and there is no point displaying it for two hundred milliseconds. The review at the end lists every one you missed, which is the part worth acting on.