Question

2.84×7.9+2.84×2+28.4×0.01的简便计算？

Answer 1

先根据小数的不变规律，把28.4x0.01，变形为2.84x0.1，再运用乘法分配律进行简便计算。
2.84x7.9+2.84x2+28.4x0.01
=2.84x7.9+2.84x2+2.84x0.1
=2.84x（7.9+2+0.1）
=2.84x（9.9+0.1）
=2.84x10
=28.4

Answer 2

2.84×7.9+2.84×2+28.4×0.01
＝2.84×7.9+2.84×2+2.84×0.1
＝2.84×（7.9+2+0.1）
＝2.84×10
＝28.4

Answer 3

因为28.4×0.01=2.84×0.1，所以原式等于2.84×7.9+2.84×2+2.84×0.1，运用乘法分配律逆运算就是2.84×（7.9+2+0.1）=28.4

Answer 4

先改28.4x0.01=2.84x10x0.01=2.84x0.1，那2.84x7.9+2.84x2+28.4x0.01=2.84x7.9+2.84x2+2.84x10x0.01=2.84x7.9+2.84x2+2.84x0.1=2.84x（7.9+2+0.1）=2.84x10=28.4

Answer 5

原式=2.84×7.9+2.84×2+2.84×10×0.01=2.84×(7.9+2+10×0.01)=2.84×10=28.4