Question

用简便计算“4.7乘3.12+1.3乘5.

Answer 1

4.7乘3.12+1.3乘5.3

=4.7*3.12+1.3*(10-4.7)

=4.7*3.12+1.3*10-1.3*4.7

=(3.12-1.3)*4.7+13

=1.82*(5-0.3)+13

=9.1-0.546+13

=21.554