小学数学:加减法计算实用技巧
式=87+13+2 =(87+13)+2 =100+2 =102 式=33+21+79 =33+(21+79) =33+100 =133 式=60+2+3+18+27 =60+(2+18)+(3+27) =60+20+30 =110 对于没有直接凑整的...
式=87+13+2 =(87+13)+2 =100+2 =102 式=33+21+79 =33+(21+79) =33+100 =133 式=60+2+3+18+27 =60+(2+18)+(3+27) =60+20+30 =110 对于没有直接凑整的...