Games

Short games for skills that are useful on their own: doing numbers in your head, estimating, judging how sure you are. Brain training mostly makes you better at the game you trained on, so each one here trains something worth being better at. Scores and streaks stay in this browser.

Mental math sprint
Sixty seconds of arithmetic that gets harder as you get faster. Misses come back with the quickest way to work them out.
Numeracy
Fermi estimation
Estimate what you can't look up, scored by how many orders of magnitude you were off.
Estimation
Calibration trainer
Answer with a confidence level and find out whether your 80% really means 80%.
Judgment
Dual n-back
Track positions and letters from n steps back. The classic working-memory task.
Working memory
Stroop and task switching
Name the ink, not the word, while the rules change under you.
Attention
Memory palace
Digit spans and word lists, with the method of loci to carry them.
Memory
Logic puzzles
A daily nonogram with exactly one solution, solvable without a guess.
Deduction
Chess tactics
Find the winning move, with a rating that keeps the puzzles at your level.
Calculation
Spot the bias
Short scenarios. Name the reasoning error hiding in each one.
Reasoning
Flashcard recall
Timed retrieval rounds over the flashcard decks, due cards first, on the same schedule as studying them.
Retention