Permutations and Combinations Part 2

4 digit numbers
For divisibility by 55 , no. should be div. by 5 and 11 both
Also, for divisibility by 11
a+c=b+5
for b=1‌‌a=2,‌‌c=4
a=4,‌‌c=2
for b=2‌‌a=3,‌‌c=4
a=4,‌‌c=3
for b=3‌‌a=6,‌‌c=2
a=2,‌‌c=6
∴6 possible four digit no.s are div. by 55
(II) 5 digit number is not possible