Question

Find the number of divisions of $1980$.
i) How many of them are multiple of $11$?

Answer 1

According to the question,
$1980=2^2\times 3^2\times 5\times 11$
No. of division,
$=(2+1)(2+1)(1+1)(1+1)$
$=3\times 3\times 2\times 2$
$=36$
No. of division of 1980 which are multiple of 11.
$=3\times 3\times 2$
$=18$