All the digits of a 50 digit positive number are 4 except for the nth digit.If the number is divisible by 13 for some choice of that nth digit, then howmany possible values can n have?
Correct Answer : E
A boy writes all the numbers from 100 to 999. The number of zeroes that he uses is 'a', the number of 5's that he uses is 'b' and the number of 8's he uses is 'c'. What is the value of b+c-a?
What is the unit's digit of the number 6256–4256
N is the smallest number that has 5 factors. How many factors does (N - 1) have??