Challenge Your Brain With Real-Time Math Battles for Grown-Ups

Adults returning to arithmetic are usually not missing knowledge — they are missing speed, because the facts have not been retrieved in twenty years and have gone from recall back to reconstruction. The route back is short: the facts are still there and rebuild much faster than they were first learned. Most people notice a difference within a fortnight of daily minutes.

Third grade has all four operations available at small numbers, which makes random mixed practice possible for the first time. The useful difficulty is choosing: deciding what a question asks before answering it. Word problems fail here not on arithmetic but on picking an operation from a keyword rather than from the situation.