Saturday, 1 February 2014

Question of the Day No. 28

Find the Number of Divisors of 420 ?

a) 24   b) 25   c) 20   d) 18    e) 21
Answers and Explanations are welcome in comments
The Correct Answer will be Given Tomorrow
Posted by at

1 comment:

  1. Unknown3 February 2014 at 00:13

    Correct Answer is 24
    Explanation : Its is very hard to count the divisors of any numbers. So note down the formula to count divisors

    420 = 42 * 10 = 7*6*2*5=7*2*2*3*5*

    So 7^1*2^2*3^1*5
    Add 1 to every power and Multiply them
    (1+1)*(2+1)*(1+1)*(1+1) = 2*3*2*2 = 24

    So the number of divisors are 24

    ReplyDelete

Subscribe to: Post Comments (Atom)