唔該幫我......

2006-11-30 1:48 am

唔該幫我......

1+2+3+...+99+100+99+88...+2+1=?

回答 (5)

2006-11-30 2:52 am

1+2+3+...+99+100+99+98...+2+1
=(1+100)*100/2+(1+99)*99/2
=101*100/2+100*99/2
=5050+4950
=10000

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2006-11-30 2:02 am

=1+2+3+...+99+100 +1+2+3+...99
=(1+100)X100/2+(1+99)X99/2
=5050+4950
=10000

Other way to calculate
1+2+3+...+100=5050
5050X2-100
=10000

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2006-11-30 2:01 am

(1+100)×(100÷2)+(1+99)×(99÷2)
=5050+4950
=10000

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2006-11-30 2:00 am

=(1+100)*100/2+(1+99)*99/2
=5050+4950
=10000

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2006-11-30 1:57 am

係10050

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