发现一个二位数平方/三位数平方的计算技巧

典座 · 发表于 2020-3-4 06:03:36

来自gmatclub的大神，看起来蛮实用，分享一下

e.g. 108^2=(100+8)^2 108^2=(100+8)^2 Write 64 on right-hand side

________ 64

Add 8 to 108 to get 116 and write that on left-hand side

11664 - Square of 108

e.g. 91^2=(100−9)^2 91^2=(100−9)^2 => ______81 => 8281
(Here, subtract 9 from 91)

Note: a could be a two digit number as well.
e.g 112^2=(100+12)^2 112^2=(100+12)^2 = ______44 => 12544
(Only last two digit of the square of 12 are written on the right hand side. The 1 of 144 is carried over and added to 112 + 12)

This is Vedic Math though the trick uses basic algebra.
(100+a)^2=10000+200a+a^2 (100+a^)2=10000+200a+a^2
(100 + 8)^2 = 10000 + 200 x 8 + 64 = 10000 + 1600 + 64 = 11664

This is a useful trick that saves time.

Maypark · 发表于 2020-3-5 04:19:28

感谢分享！

典座 · 发表于 2020-3-5 13:39:21

Maypark 发表于 2020-3-5 04:19
感谢分享！

发现一个二位数平方/三位数平方的计算技巧

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