project-euler/Trashed attempts/820 N-th digit of Reciprocals.sf

#!/usr/bin/ruby

# N-th digit of reciprocals
# https://projecteuler.net/problem=820

# Naive approach.

func S(n) {
    var m = 10**n
    sum(1..n, {|k| idiv(m,k)%10 })
}

say S(7)
say S(100)
say S(1e7)