19.9乘108减1.99乘70减19.9用简便方法计算怎么写?
问题描述:
19.9乘108减1.99乘70减19.9用简便方法计算怎么写?
答
19.9乘108减1.99乘70减19.9
=19.9乘108减19.9乘7减19.9
=19.9×(108-7-1)
=19.9×100
=1990