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New Member
加入日期: Nov 2008
文章: 9
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快速算出一個數字的平方
43^2 = ?
43-25=18 50-43=7 7*7=49 43^2 = 1849 46^2=? 46-25=21 50-46=4 4*4=16 46^2 = 2116 50以前都適用,有人知道原理嗎? |
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2012-05-26, 02:26 AM
#1
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Senior Member
 
加入日期: May 2003
文章: 1,179
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51~99
51^2 51 - 49 = (100-51) ------ = (0)2(00) = 0200 49*49 49-25 = 24 50-49 = 1 1*1 = 1 2401 2401 + 0200 -------- = 2601 http://cashflowco.hubpages.com/hub/...square-a-number
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此文章於 2012-05-26 03:02 AM 被 951 編輯. |
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2012-05-26, 03:01 AM
#2
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Power Member
加入日期: Aug 2000 您的住址: CA, USA
文章: 553
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(a-25)*100 + (50-a)^2
= 100*a - 2500 + 2500 - 100*a + a^2 = a^2 應該是所有數字都適用 引用:
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2012-05-26, 03:02 AM
#3
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Regular Member
 
加入日期: Jan 2008
文章: 95
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引用:
???? 如果算2的平方的話 2 -25 = -23 50 - 2 = 48 48*48 = 2304 所以2*2 = -232304? 這沙小?  |
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2012-05-26, 03:53 AM
#4
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*停權中*
加入日期: Oct 2008
文章: 317
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-23跟23不就抵消了
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2012-05-26, 05:00 AM
#5
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