Trial division discoverer or inventor Fibonacci
Trial division is the most laborious but easiest to understand of the integer factorization algorithms.  The essential idea behind trial division tests to see if an integer n, the integer to be factored, can be divided by each number in turn that is less than n.  For example, for the integer n = 12, the only numbers that divide it are 1, 2, 3, 4, 6, 12.  Selecting only the largest powers of primes in this list gives that 12 = 3 × 4 = 3 × 22.
Trial division was first described by Fibonacci in his book Liber Abaci (1202).
discoverer inventor creator pioneer innovator