What the tool does, how to run it, and what to expect from the result.
Each divisor has a shortcut: 3 and 9 check the digit sum, 4 the last two digits, 8 the last three, 11 the alternating digit sum, 6 and 12 combine two rules. 2520 is divisible by every number from 1 to 10, the smallest number that is.
A quick way to understand who this helps, what it solves, and where it connects next.
Students, teachers and anyone checking a calculation.
Using the divisibility test without installing anything or signing up.
Short answers for the questions people usually have before trying a utility like this.
Add the digits; if the sum is divisible by 3, so is the number. 2520: 2 + 5 + 2 + 0 = 9.
Alternately add and subtract the digits; if the result is divisible by 11 (including 0), so is the number. 1331: 1 − 3 + 3 − 1 = 0.
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Enter your numbers and the result updates live in your browser. Nothing is uploaded and no server is used.
Calculations run locally in your browser; nothing is uploaded.