Stage 6 · Big numbers & speed
Squares to 25
Ends in 5: tens × next number, then 25.
How to do it
Method
Ends in 5: tens × next number, then 25
25²: 2 × 3 = 6 → 625
Another way
Column multiplication
25² = 25 × 25 = 625
In full
Learn 1² to 25² — a lot of later tricks borrow from them. Squares ending in 5 are easiest: 25² → 2 times the next number, 3: 2×3=6, stick 25 on → 625; 35² → 3×4=12 → 1225. You can also multiply in columns: 25² is 25 × 25, which gives the same 625.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
3²
Show the answer and working
Answer: 3² = 9
3² is 3 × 3: ×3 is a double and one more, 3 × 2 = 6, 6 + 3 = 9
Example 2
6²
Show the answer and working
Answer: 6² = 36
6² is 6 × 6: ×6 is ×3 doubled, 6 × 3 = 18, 18 × 2 = 36
Example 3
7²
Show the answer and working
Answer: 7² = 49
7² is 7 × 7: ×7 is ×5 and ×2, 7 × 5 = 35, 7 × 2 = 14, 35 + 14 = 49
Example 4
24²
Show the answer and working
Answer: 24² = 576
24² is 24 × 24: split 24 into 20 and 4, 20 × 24 = 480, 4 × 24 = 96, 480 + 96 = 576
Practise squares to 25 in the game →Stage 6 · Big numbers & speed · Free to start, unlimited questions, no download