题目内容
【题目】用递等式计算(能简算的要简算). ①102×4.5
②7.8×6.9+2.2×6.9
③4×37×0.25
④8×(20﹣1.25)
【答案】 ①459 ②69 ③37 ④150
【解析】解:①102×4.5 =(100+2)×4.5
=100×4.5+2×4.5
=450+9
=459
②7.8×6.9+2.2×6.9
=6.9×(7.8+2.2)
=6.9×10
=69
③4×37×0.25
=4×0.25×37
=1×37
=37
④8×(20﹣1.25)
=8×20﹣8×1.25
=160﹣10
=150
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