Mental math technique
Learn and drill the base 100 multiplication shortcut.
(100 − a)(100 − b) · 60 second drill
Start free practiceNo account. No card. Your first run starts here.
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Use the keyboard for every action. Your response time is measured with performance.now().
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Traintheoperationthatcostsyoupointsbeforetheclockexposesitagain.
Preparation guide
Practice in one uninterrupted block and use the same keyboard controls you will use on test day. Speed improves when answer entry becomes automatic.
Review both accuracy and response time. A slow correct answer can still reveal the operation family that will cap your score under a fixed deadline.
Repeat weak families separately, then return to a full mixed benchmark. This keeps technique work distinct from pacing practice.
Answers before signup
Use the base 100 identity to turn two awkward products into one subtraction and one small product.
The embedded practice set is free and starts without signup.
Yes. Question construction uses scaled integers or exact rational arithmetic, not raw floating point expressions.
Yes. Typed mode accepts forms such as 3/8 as well as exact terminating decimals.
Use short focused sets until accuracy is stable, then test transfer in a longer mixed assessment.
The arena records response time, correctness, operation family, domain, and question shape for each attempted item.
Keep question-level timing locally and expose the family slowing you down.