速算與巧算的奧數題

例題:

速算與巧算的奧數題

(1)372÷162×54(2)132×288÷(24×11)

(3)616÷36×18÷22(4)14×44×104

(5)8100÷5÷90×15(6)7777×3333÷1111

(7)(4+7+…+25+28)-(2+5+…+23+26)

(8)199+1999+19999+199999.

考點

乘除法中的巧算;加減法中的巧算.

分析:

(1)、(2)利用除法的簡算;

(3)、(4)、(5)利用乘法的交換律;

(6)利用乘法的交換和結合律;

(7)前面括號中的`每個數比後面括號中的數大2,然後利用加法的交換和結合律;

(8)最新的國小四年級速算與巧算奧數題及答案:分別用整數200,2000,20000,200000減1,然後利用加法的交換和結合律.

解答:

(1)372÷162×54,

=372÷(162÷54),

=372÷3,

=124;

(2)132×288÷(24×11),

=132×288÷24÷11,

=132÷11×288÷24,

=(132÷11)×(288÷24),

=12×12,

=144;

(3)616÷36×18÷22,

=616×18÷36÷22,

=14;

(4)14×44×104,

=2×7×4×11×8×13,

=(7×11×13)×(2×4×8),

=1001×64,

=64064;

(5)8100÷5÷90×15,

=8100×15÷5÷90,

=(8100×15)÷(5×90),

=121500÷450,

=270;

(6)7777×3333÷1111,

=1111×7×1111×3÷1111,

=7×3×1111×1111÷1111,

=(7×3)×1111×(1111÷1111),

=21×1111×1,

=23331;

(7)(4+7+…+25+28)-(2+5+…+23+26),

=4+7+…+25+28-2-5-…-23-26,

=(4-2)+(7-5)+…+(25-23)+(28-26),

=2+2+…2+2,

=2×9,

=18;

(8)199+1999+19999+199999,

=200-1+2000-1+20000-1+200000-1,

=(200+2000+20000+200000)-(1+1+1+1),

=222200-4,

=222196.