Bunuel
When a positive integer n is divided by 13, what is the remainder?
(1) n + 1 is divisible by 13
(2) n + 14 is divisible by 13
Sol: Option-DAsked: Remainder R, when a positive integer n is divided by 13 :
Mathematically, n = 13k + R , R = ?
St-1:n + 1 is divisible by 13
(n+1) = 13m + 0
n = 13m - 1
It can be further written as: n = 13m - 13 + 13 - 1 = 13(m-1) + 12 ;
Remainder is 12
e.g. n+1 = 12 + 1 = 13 , where n=12 , 12/13 leaves a remainder of 12
For n + 1 = 26 = 25 + 1 , n = 25, 25/13 leaves a remainder of 12
Statement is sufficientSt-2:n + 14 is divisible by 13
(n+14) = 13m + 0
n = 13m - 14
n = 13m - 13 -1 = 13(m-1) - 1 ;
n = 13(m-1) -13 + 13 -1
n = 13(m-2) + 12
Remainder is 12
e.g. n+14 = 12 + 14 = 26 , where n=12 , 12/13 leaves a remainder of 12
For n + 1 = 39 = 25 + 14 , n = 25, 25/13 leaves a remainder of 12
Statement is sufficient