Question

6.12×2.1 61.2×0.79,的简便计算,为什么这么算?

Answer 1

6.12×2.1=61.2×0.21
所以6.12×2.1+61.2×0.79=61.2×（0.21+0.79）=61.2×1=61.2
这个叫凑整，是数学中的一种简便方法

Answer 2

题目好像写错了，应该是6.12*2.1+61.2*0.79=6.12*2.1+6.12*7.9=6.12*(2.1+7.9)=61.2;哈哈，合并同类项

Answer 3

6.12×2.1=(6+0.12)×(2+0.1)=6×2+0.12×2+6×0.1+0.12×0.1
=12+0.24+0.6+0.012
=12.852
61.2×0.79=(60+1.2)×(0.8-0.01)
=60×0.8+1.2×0.8-60×0.01-1.2×0.01
=48+0.96-0.6-0.012
=48.348

Answer 4

追答

拆，补，把一个数变简单，比如变成整数之类的。