计算下列各题.(能简算的要简算)(1)7.8×15+2.2×20%(2)0.5×[515÷﹙78-116﹚](3)(198+32×72)-2472÷24(4)425×[2.6+34-(0.65+134)]÷234.-数学
题文
计算下列各题.(能简算的要简算) (1)7.8×
(2)0.5×[5
(3)(198+32×72)-2472÷24 (4)4
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答案
(1)7.8×
=7.8×0.2+2.2×0.2, =(7.8+2.2)×0.2, =10×0.2, =2; (2)0.5×[5
=0.5×[
=0.5×[
=0.5×
=3.2; (3)(198+32×72)-2472÷24, =(198+2304)-103, =[(200-2)+(2300+4)]-103, =[200+2300+(4-2)]-103, =2500+2-(100+3), =2500-100-(3-2), =2400-1, =2399; (4)4
=4
=4
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