Continuing our theme from last time. The Finnish social security number (FSSn) has the form xxxxxxyzzzq, where the check digit is q.
If you want to check if the FSSn is real the check digit is matched to the remainder of xxxxxxzzz / 31. The check digit can be numbers from 0-9 followed by letters A, B, C, D, E, F, H, J, K, L, M, N, P, Q, R, S, T, U, V, W, X, Y. If the remainder is a number