四年级上册数学【运算律】简便运算例题解析
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简介
加法交换律、加法结合律 ①325+480+75 =325+75+480 =400+480 =880 ②78+36+164 =78+(36+164) =78+200 =278 ③425+14+186 =425+(186+14) =425+200 =625 减法的性质 ①868-52-48 =868-(52+48) =868-100 =768 ②787-(87-29) =787-87+29 =700+29 =729 ③141-19-81 =141-(19+81) =141-100 =41
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