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Number System
by Abhishek TG - Tuesday, 12 August 2014, 10:27 PM
  If n is a natural number , find the possible terminating digits of n^2 + n in base 5 ?

Plz explain
Re: Number System
by Raghav Lakhotia - Wednesday, 13 August 2014, 03:36 PM
  0,1,2 ?
Re: Number System
by Raghav Lakhotia - Wednesday, 13 August 2014, 03:39 PM
  see, n^2 + n will always be even
as odd^2 + odd = even
even^2 + even = even
hence will end in 0,2,4,6,8

now n^2 + n = n(n+1)
now n*(n+1) can end in 0,2,6 only
0 = > 4*5, 5*6
2 = > 1*2, 3*4, 6*7, 8*9
6 = > 2*3, 7*8

hence only 0, 2, 11(for 6) smile
Re: Number System
by Abhishek TG - Wednesday, 13 August 2014, 05:50 PM
  thanx