How to Divide by 25 in Your Head
Divide by 25 by multiplying by 4, then dropping two zeros.
800 ÷ 25 = 32
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Every 100 holds four 25s, so 8 hundreds hold 8 × 4 of them.
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Drop the two zeros: 8. Then ×4 by doubling twice: .
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For 850, the 800 gives 32 and the 50 left over holds two more 25s: 850 ÷ 25 = 34.
How do you divide by 25 in your head?
To divide by 25, multiply by 4 and divide by 100. For 800 ÷ 25, multiply first: 800 × 4 = 3200, then 3200 ÷ 100 = 32.
It works because 25 × 4 = 100, so every hundred holds exactly four 25s, and the answer is four times the number of hundreds.
When the number is not a whole number of hundreds, the leftover adds one for each 25 it holds: 850 ÷ 25 is 32 for the 800, plus 2 for the 50, so 34. A leftover smaller than 25 becomes a decimal, and the multiply-by-4 route handles that without any extra step: 810 ÷ 25 is 810 × 4 = 3240, then 3240 ÷ 100 = 32.4. Check by multiplying back, remembering that 25 is 100 ÷ 4: 32.4 × 100 ÷ 4 = 3240 ÷ 4 = 810.
How do you divide bigger numbers by 25?
Count the hundreds, multiply by 4, then add one for each 25 left over. For 1350 ÷ 25, 13 hundreds give 13 × 4 = 52, and the 50 left over holds two more 25s, so 54. For 2475 ÷ 25, 24 × 4 = 96, and 75 holds three, so 99.
Why does it work?
25 × 4 = 100, so dividing by 25 is the same as multiplying by 4 and dividing by 100. Multiplying by 4 first is the same calculation in a different order: 1350 × 4 = 5400, and 5400 ÷ 100 = 54. Choose whichever order keeps the numbers small.
Your turn
Three to try in your head. Tap what you get.
300 ÷ 25 = ?
2150 ÷ 25 = ?
1225 ÷ 25 = ?
All 36 shortcuts: the Magic Tricks library.