Squaring Numbers Ending in 5
- Trick / Shortcut
- Squaring Numbers Ending in 5
- Topic
- Squares & Cubes
- How It Works
For any number ending in 5:
- Take the digit(s) before 5, let this be $n$.
- Multiply $n$ by $(n+1)$.
- Append
25to the result from step 2.
Formula: $(n5)^2 = n \times (n+1)$ followed by $25$
- Example
$35^2$: $n=3$. Calculate $3 \times (3+1) = 3 \times 4 = 12$. Append $25$. Result: $\textbf{1225}$
$75^2$: $n=7$. Calculate $7 \times (7+1) = 7 \times 8 = 56$. Append $25$. Result: $\textbf{5625}$
$125^2$: $n=12$. Calculate $12 \times (12+1) = 12 \times 13 = 156$. Append $25$. Result: $\textbf{15625}$