How many factors of $2^4 × 5^3 × 7^4$ are odd numbers?
Solution:Option(A) is correct
Any factor of this number should be of the form $2^a × 3^b × 5^c$.
For the factor to be an odd number, $a$ should be $0$.
$b$ can take values $0,1, 2,3$ and $c$ can take values $0, 1, 2,3, 4.$
Total number of odd factors,
$= 4 × 5$
Error(s) Found !!!
VEERARAGAVAN C S (Oct 02'14 at 10:17)
there is a mistake in the first line.
it should be $2^a \times 5^b \times 7^c$. Since none of the factors of the given number is a multiple of 3
Fill out the name first.
Posting as #name, Edit Details
To write Maths use $ or $$ delimiters. (TeX)Ex: $ax^2+bx+c=0$.
Help us keep afloat. Consider making a small contribution.
To appreciate the effort Lofoya.com is putting, Please like our page and help us spread the word.