Search found 3 matches
n^2 - 1 can be represented as (n-1)(n+1). now if n = odd n-1 and n+1 represent two consecutive even number. so n - 1 = 2 * x where x = any integer n + 1 = (n-1) + 2 = 2*x + 2 = 2 (x+1) Case1: if x = odd, x+1 will be even. So n+1 will be divisible by 2 * (Even Number) which means 4 Also n-1 will be d...
- by theadityajamwal
Thu Jul 14, 2011 1:58 am- Forum: Data Sufficiency
- Topic: Remainder Prob
- Replies: 74
- Views: 40066
Q) remainder of 8*10^k + j when divided by 9. Rephrasing the Q gives me [( 9 - 1 ) * 10^k + j] / 9 ( 9 * 10^k - 10^k + j )/9 Now 9 * 10^k will always be divisible by 9. So we can omit that and are left with ( j - 10^k )/9 [j - (9+1)^k ]/9 Now for any equation (a+b)^n, every term will be divisible by...
- by theadityajamwal
Wed Jul 13, 2011 1:45 am- Forum: Data Sufficiency
- Topic: Integer Properties - DS
- Replies: 102
- Views: 44445
Dont know if its the best way but i always follow this in Work/Time problems.. Took the LCM of 12, 15 and 18 as 180. Now Rate of X = 180/12 = 15 Rate of Y = 180/15 = 12 Rate of Z = 180/18 = 10 Time taken by X to finish 180 units = 12 Time taken by Y nd Z to finish 180 units = 180/ (12+10) = 180/22 S...
- by theadityajamwal
Fri Jul 08, 2011 11:17 pm- Forum: Problem Solving
- Topic: og math # 130
- Replies: 132
- Views: 58249