Page numbers
Algebra
Level
pending
All the page numbers of a book starting from 1 was added. One page number was mistakenly added twice and the sum resulted in 1000. Find that page number.
10
44
45
12
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1 solution
Page numbers will form an AP 1, 2, 3, ... , n for a = 1, d = 1 sum of terms = n(n + 1)/2 < 1000 maximum n= 44 for which sum = (44 x 45)/2 = 990 So page number added twice = 1000 - 990 =10