简算.
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| (1)648-187-113 =648-(187+113) =648-300 =348; (2)375-(175+94) =375-175-94 =200-94 =106; (3)642-298 =642-(300-2) =642-300+2 =342+2 =344; (4)486+598 =486+600-2 =1086-2 =1084. |
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a.12×(4+25)[ ]
a. 47+(14×5)(1)35+65=
65+35=
35+65○65+35