如何巧算13.5乘以9.9+16.5乘以10.1

3个回答

原式=13.5×(10-0.1)+16.5×(10+0.1)
=13.6×10+16.5×10-13.5×0.1-16.5×0.1
=10×(13.5+16.5)+0.1×(-13.5+16.5)
=10×30-0.1×3=300-3=299.7