第113页 - 经纶学典学霸五年级数学上下册【江苏国标】

3.79×0.38+1.59×6.21+3.79×1.21

=3.79×(0.38+1.21)+1.59×6.21

=1.59×(3.79+6.21)

=15.9

=5.78×8.8+6.15×4.22-5.78×2.65

=5.78×(8.8-2.65)+6.15×4.22

=5.78×6.15+6.15×4.22

=6.15×(5.78+4.22)

=61.5

0.4321

0.04321

用m代替0.25+0.258,用n代替0.25+0.258+0.2589

. (1+0.25+0.258)×(0.25+0.258+0.2589)-(0.25+0.258)×(1+0.25+0.258+0.2589)

=(1+m)×n-m×(1+n)

=n-m

=0.2589