Question

10．简算：

①69.43-1.98	②102.31×59
③57.5-14.25-15	④60×102.31+40×102.31．

Answer 1

分析 ①将算式变形为69.43-2+0.02简便计算；
②④根据乘法分配律简便计算；
③从左往右依次计算即可求解．

解答 解：①69.43-1.98
=69.43-2+0.02
=67.43+0.02
=67.45
②102.31×59
=102.31×（60-1）
=102.31×60-102.31
=6138.6-102.31
=6036.29
③57.5-14.25-15 
=43.25-15
=28.25
④60×102.31+40×102.31
=（60+40）×102.31
=100×102.31
=10231

点评 考查了运算定律与简便运算，四则混合运算．注意运算顺序和运算法则，灵活运用所学的运算定律简便计算．