Question

123乘以0.45+12.3乘以0.7减去1.23乘以212,怎样快速算?

Answer 1

123乘以0.45=12.3*4.5 12.3乘以0.7 1.23乘以212=12.3*21.2 所以123乘以0.45+12.3乘以0.7减去1.23乘以212=12.3*4.5+12.3乘以0.7+1.23乘以212=12.3*21.2= 12.3乘以（4.5+0.7-21.2）=12.3*（-16）=-196.8