问题 解答题

用递等式计算(能巧算的要巧算

(125+83)×32

16×78-(1440÷45+29)

513×63+36×513+513

216×27÷81+712÷89

125×320×25

5580÷[30+12×(361-356)].

答案

(1)(125+83)×32,

=208×32,

=(200+8)×32,

=200×32+8×32,

=6400+256,

=6656;

(2)16×78-(1440÷45+29),

=16×78-(32+29),

=16×78-61,

=1248-61,

=1187;

(3)513×63+36×513+513,

=513×(63+36+1),

=513×100,

=51300;

(4)216×27÷81+712÷89,

=5832÷81+712÷89,

=72+8,

=80;

(5)125×320×25,

=125×(8×40)×25,

=(125×8)×(40×25),

=1000×1000,

=1000000;

(6)5580÷[30+12×(361-356)],

=5580÷[30+12×5],

=5580÷[30+60],

=5580÷90,

=62.

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