Q. The number of natural numbers lying between 1012 and 23421 that can be formed using the digits 2,3, 4, 5, 6 (repetition of digits is not allowed) and divisible by 55 is
Solution:
4 digit numbers
$a+c=b+5 $
$\text { for } b=1 a=2, c=4 $
$ a=4, c=2$
$\text { for } b=2 a=3, c=4$
$ a=4, c=3$
$\text { for } b=3 a=6, c=2 $
$ a=2, c=6$
$\therefore 6$ possible four digit no.s are div. by 55
(II) 5 digit number is not possible
