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计算:(1)454十999×999十545(2)999十998十997十996十1000十1004十1003十1002十1001(3)125×198÷﹙18÷8)(4)2772÷28+34965÷35(5)1+2+3+4…+99+100.

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(1)454+999×999+545
=454+999×(1000-1)+545,
=454+999×1000-999+545,
=454+545-999+999000,
=999-999+999000,
=999000;

(2)999+998+997+996+1000+1004+1003+1002+1001.
=(999+1001)+(998+1002)+(997+1003)+(996+1004)+1000,
=2000+2000+2000+2000+1000,
=9000;

(3)125×198÷﹙18÷8),
=125×198÷18×8,
=(125×8)×(198÷18),
=1000×11,
=11000;

(4)2772÷28+34965÷35
=(2800-28)÷28+(35000-35)÷35,
=100-1+1000-1,
=99+999,
=1098;

(5)1+2+3+4…+99+100,
=(1+100)+(2+99)+…+(50+51),
=101×50,
=5050.