Question

A 4035-digit number is a multiple of 13. Its first 2017 digits are all 5s, and its last 2017 digits are all 6s. What is the middle digit?

Answer 1

Answer:

The question is from Permutation and Combination. Another question which combines number theory with combinatorics. We need to find out the number of 5 digits which are multiple of 15 and satisfies the given conditions. This section hosts a number of questions which are on par with CAT questions in difficulty on CAT Permutation and Combination, and CAT Probability.