Bài 2: Tính nhanh: a) 4524 – (864 – 999) – (36 + 3999) b) 1000 – (137 + 572) + (263 – 291) c) -329 + (15 – 101) – (25 – 440) d) (-8).25.(-2).4.(-5).12

Bởi

Bài 2: Tính nhanh:
a) 4524 – (864 – 999) – (36 + 3999)
b) 1000 – (137 + 572) + (263 – 291)
c) -329 + (15 – 101) – (25 – 440)
d) (-8).25.(-2).4.(-5).125
e) (-167).83 + 167.(-17) – 33
f) 21.49 + 21.66 – 21.15

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  1. @nguyenngoclananhpt

    $a, 4524-(864-999)-(36+3999)$
    $= 4524-864+999-36-3999$
    $= 4524-(3999-999)-(864+36)$
    $=4524-3000-900$
    $=1524-900$

    $=624$
    $b, 1000-(137+572)+(263-291)$
    $= 1000-137-572+263-291$
    $=1000+263-(137+572+291)$
    $=1000+263-1000$

    $=263$
    $c, -329+(15-101)-(25-440)$
    $= -329+15-101-25+440$
    $=440-(329+101)-(25-15)$
    $=440-430-10$

    $=0$

    $d, (-8).25.(-2).4.(-5).125$
    $=[(-8).125].(25.4).[(-2).(-5)]$
    $=-1000.100.10$
    $=-1000000$

    $e, (-167).83+167.(-17)-33$

    $=[(-167).83+167.(-17)]-33$

    $=[(-83).167+167.(-17)]-33$

    $=167.[(-83)+(-17)]-33$

    $=167.(-100)-33$

    $=-16700-33$

    $=-16733$

    $f) 21.49 + 21.66 – 21.15$

    $= 21.(49+66-15)$

    $= 21 . 100$

    $= 2100$

     

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