Compute 105² without direct multiplication:
- 10025
- 10525
- 11025
- 11225
Show answer and solution
Correct answer: C. 11025
105² = (100 + 5)² = 100² + 2·100·5 + 5² = 10000 + 1000 + 25 = 11025. Alternatively, using the (a5)² rule: a = 10, a(a+1) = 10·11 = 110
We have so 105² = 11000 + 25.
So so 105² = 11025.