先估计商是几位数,再计算,并验算.计算时应注意什么?728÷7=409÷8=842÷8

2025-03-16 21:20:57
推荐回答(2个)
回答1:

(1)728÷7=104;(商是三位数)


(2)409÷8=51…1;(商是两位数)


(3)842÷8=105…2;(商是两位数)

回答2:

答案:104;51…1;105…2
解析:
试题分析:根据除数是一位数的整数除法法则,先用除数试除被除数的前一位数,如果大于或大于除数,说明前一位数够除,商的最高位是百位,商就是三位数,如果不够除,就看被除数的前两位数,那么商的最高位是十位,所以商是两位数,
再根据除数是一位数的除法竖式计算的方法求解,并根据除法验证乘法的方法求解.
解:(1)728÷7=104;(商是三位数)

(2)409÷8=51…1;(商是两位数)

(3)842÷8=105…2;(商是两位数)
点评:本题考查了两位数除以一位数竖式计算的方法和试商的方法,以及乘法验证除法的方法,要注意商中间有“0”的除法和有余数的验算方法.

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