①（12.5-0.125）×8
=12.5×8-0.125×8
=100-1
=99；
②5.25×
-0.75÷51 5
=(5.25?0.75)×
1 5
=4.5×
1 5
=0.9；
③253×102
=253×100+253×2
=25300+506
=25806；
④
÷[（1 5
+2 3
）×15]1 5
=
÷[1 5
×15+2 3
×15]1 5
=
÷[10+3]1 5
=
÷131 5
=
×1 5
1 13
=
．1 65
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