This is a 20-problem addition board: every sum is on screen at once, and you clear them in any order you like. Each problem adds two whole numbers between 12 and 89 — think "37 + 48" — so it's real two-digit mental math with carrying, not single-digit warmups.
It suits anyone who wants a calm, untimed-feeling practice round. There's a clock, but it only counts up — your finish time is a personal stat to beat, never a limit. If you're training for the Arithmetic Sprint, this board is the natural first stop.
How to play
All 20 sums are visible from the start — solve them in whatever order you spot first.
Type into the single answer box; the moment your number exactly matches an unsolved answer, it commits automatically. No Enter needed.
Pressing Enter on a wrong number just shakes the box and clears it — there's no penalty and nothing is marked wrong.
The timer starts on your first keystroke and counts up; it's a stopwatch, not a countdown.
Give up any time to see your result — then use "Reveal answers" to see the sums you missed.
What counts in this quiz
20 addition problems per run, freshly generated each time you play — no two boards are alike.
Both numbers are always between 12 and 89, so answers range from 24 up to 178.
Every board is built so no two answers collide (and no answer is the start of another) — each number you type maps to exactly one problem.
What's not included — and why
No single-digit sums — operands start at 12, because "3 + 4" teaches nothing and tiny answers would clash with the unique-answer rule.
No negative numbers or decimals — this board is whole-number addition only.
Good to know
The + sign first appeared in print in 1489, in a German arithmetic book by Johannes Widmann — before that, writers spelled out the Latin word "et".
Legend says a young Carl Friedrich Gauss summed 1 through 100 in seconds by pairing them into fifty 101s: 5,050.
Because addition is commutative, starting from the larger number and counting up is always legal — a trick most people discover before anyone teaches it.