Question 5
A number is called a palindrome if it reads the same from left to right and from right to left; examples include $7,11,121,1221,\ldots$. Let $\overline{abccba}$ be a six-digit palindrome.
a) Prove that $\overline{abccba}$ is divisible by 11.
b) How many such six-digit palindromes are divisible by 91?
a) Prove that $\overline{abccba}$ is divisible by 11.
b) How many such six-digit palindromes are divisible by 91?