How to square numbers ending in 5 in your head

For ages 7 to 10 (Years 3 to 5) · 2-minute read · free worksheet

Any number ending in 5 can be squared in two quick steps. It looks like magic and builds confidence with bigger numbers.

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Worksheet includes an answer key for grown-ups

How it works

  1. Take the tens digit.
  2. Multiply it by the next number up.
  3. Write 25 on the end.

Worked example

35²: 3 × 4 = 12. Write 25 on the end: 1225.

Top tip

75²: 7 × 8 = 56, then 25: 5625. Remember to write 25, not add it.
How to square numbers ending in 5 in your head: 35² = ? 3 × 4 = 12, then 25: 1225

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