Permutations and Combinations Part 1

Form of six digit palindrome numberxyzzyx
This will be divisible by 55
Hence, x = 5
and 5 5 yzzy will be divisible by 11.
⇒(5+z+y)−(y+z+5) is divisible by 11
which is true for all values of y and z
⇒ y and z can be chosen in 10×10 ways
Number of such number = 100