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简便计算:12.4-12.4×0.25,0.25×9+1÷8.

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/03/28 19:07:42
简便计算:12.4-12.4×0.25,0.25×9+1÷8.
12.4-12.4*0.25
=3.1*4 - 3.1*4*0.25
=3.1*4 - 3.1*(4*0.25)
=3.1*4-3.1
=3.1*(4-1)
=3.1*3
=9.3
0.25*9+1÷8
=(0.25*9*8 + 1÷8*8) ÷ 8
=(0.25*4*9*2 + 1)÷8
=(18+1)÷8
=19÷8
=2.375