 In other words, multiples of the smaller number "r""k"−1 are subtracted from the larger number "r""k"−2 until the remainder "r""k" is smaller than "r""k"−1.In the initial step ("k" = 0), the remainders "r"−2 and "r"−1 equal "a" and "b", the numbers for which the GCD is sought.In the next step ("k" = 1), the remainders equal "b" and the remainder "r"0 of the initial step, and so on.