四年级数学•《运算律》简便计算

四年级数学•《运算律》简便计算


简介:
一、加法交换律:a+b+c=a+c+b 12+36+18 =12+18+36 =30+36 =66 76+345+24 =76+24+345 =100+345 =445 53+19+7= =53+7+19 =60+19 =79