7.28+(6.78-5.46)
=7.28+(6.72+0.06-5.46)
=7.28+6.72+0.06-5.46
=(7.28+6.72)+(0.06-5.46)=14-5.4=8.6
7.28+(6.78-5.46)
=(7.28+6.72)-(5.46-0.06)
=14-5.4
=8.6
7.28+(6.78—5.46)
=7.28+1.32
=9.6
解:
7.28十(6.78一5.46)
=7.22+0.06+6.78-5.46
=7.22+6.78+0.06-5.46
=14-5.4
=8.6
按部就班进行运算是最简便的运算:
7.28十(6.78一5.46)
=7.28+1.32
=8,6