Find combinations of two digits I am in a puzzle that which is generated by one of my friend .
She gave me last 4 numbers of her mobile phone & i want to find the first 6 numbers.
I guessed the first 4 letters.
Assume that AAAA is the first 4 letters and MMMM is the last 4 letters and XX is the 2 letters after the first 4 letters .
So her number is 10 digit soit would be AAAAXXMMMM
I know AAAA and MMMM and now i have to find XX .
I know getting the exact value is impossible but i think that i can get the combinations of XX [2 digits].
How can i get this ?
Thank you.

You should apply formula of permutations with repetition .
So , number of permutations in this particular case is given by :
$N=10^2$
