Question

Tính nhanh:

a) 21.10+21.9+21.12+21.20 - 10.9+10.8

b)2²:2²=?

Answer 1

a)21*10+21*9+21*12+21*20-10*9+10*8=21*(10+9+12+20)-10(9+8)=21*51-10*17=1071-170=901

b)2²/2²=1

Answer 2

a) 21.10+21.9+21.12+21.20 - 10.9+10.8

=21.(10+9+12+20)-10.(9+8)

=21.51-10.17

=1071-170

=901

b)2²:2²

=4:4

=1