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For all positive integers n, the function rev(n) reverses the digits of n. For example, rev(205) = 502 and rev(12340) = 04321 = 4321. Compute the least positive integer m such that gcd(m, rev(m)) = 13.

If n is an integer greater than 1, then show that nⁿ⁻¹−1 is divisible by (n−1)².

If:

2a = 3
3b = 4
4c = 5
5d = 6

Then, find the value of a*b*c*d