3×1点5×2加3×1点25×2加1.25乘以1.25乘以二

Question

如题所述

Answer 1

3*1.5*2+3*1.25*2+1.25*1.25*2
=3*3+3*2.5+1.25*2.5
=9+2.5*(3+1.25)
=9+2.5*(4+0.25)
=9+10+0.625
=19.625

15*15=225 25*25=625 个位是5的两位数的乘法计算是有诀窍的，所以2.5*0.25就直接计算了的。