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# help

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A boy starts adding consecutive natural no.s starting from 1. After some time, ​he reaches a total sum of 1000 when he realises that he has double counted a number. Find the number double counted.

Jun 26, 2020

#1
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1000 x 2 = 2000

Sqrt(2000) =~45

[45 x 46] / 2 =1035

1035 - 1000 =35 - The number that was counted twice

Jun 26, 2020
#2
+24609
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$$\sum_{0}^{44}$$ n =990

$$\sum_{0}^{45}$$ n = 1035          HE MUST HAVE COUNTED '10'  TWICE !

Jun 26, 2020