用递等式计算(能巧算的要巧算)13×102+87125×123×8(537-5002÷61)×12613×29-29×513832÷52+52×11(1974+3684)÷(84-38)
(1)13×102+87, =13×(100+2)+87, =13×100+13×2+87, =1300+26+87, =1300+(26+87), =1300+113 =1413; (2)125×123×8, =(125×8)×123, =1000×123, =123000; (3)(537-5002÷61)×12, =(537-82)×12, =455×12, =5460; (4)613×29-29×513, =(613-513)×29, =100×29, =2900; (5)832÷52+52×11, =16+572, =588; (6)(1974+3684)÷(84-38), =5658÷46, =123. |