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Square Root Sprint shows a perfect square and asks for its root. Sixty seconds, one number at a time, no multiple choice. The squares up to 25 × 25 are the single most useful block of facts in mental arithmetic, because every multiplication near one of them can be reached in a step — and this is the drill that gets them from recognised to recalled.
Pick a range — up to 144, up to 400, or the full set to 625 — and press Start.
A square appears; type its square root.
Correct answers advance immediately and the clock keeps running.
A wrong answer shows the working before moving on.
Your score is roots answered correctly inside the minute.
Recall of the square numbers in both directions. Squaring and rooting are the same fact read forwards and backwards, and drilling the backwards direction is what makes estimating any square root fast — you bracket the number between two squares you already know.
Learn the last digits. A perfect square never ends in 2, 3, 7 or 8, and a square ending in 6 has a root ending in 4 or 6.
Anchor on the round ones: 100, 400 and 900 are 10², 20² and 30². Everything else sits between two anchors.
Squares of numbers ending in 5 are easy: 35² is 3 × 4 = 12 with 25 on the end, so 1,225.
Say the answer before you read the whole number. The first digit or two usually narrows it to one candidate.
The number that, multiplied by itself, gives the number you started with. The square root of 144 is 12, because 12 × 12 = 144.
Yes — every question in the drill has a whole-number answer. For roots that do not come out exactly, the square root pages work through the estimate by hand.
Up to 12² is the minimum worth having, because it makes every nearby multiplication one addition away. Up to 25² covers almost every estimate you will need.
Because the backwards direction is the one that comes up. Estimating a root, simplifying a surd and checking an area all start from the number and ask for the side.