一、用简便方法求和: ① 536+(541+464)+459 =(536+464)+(541+459) =1000+1000 =2000 ② 588+264+148 =588+(12+252)+148 =(588+12)+(252+148) =600+400 =1000 ③ 8996+3458+7546 =(8996+4)+(3454+7546) =9000+11000 =20000