All we have to do is carry out the algorithm in sequential steps one after the
other. The only thing missing in this recipe, usually present in a mathematical
algorithm, is a loop, a tool to deal with recursion. Hopefully we won’t have to
cook the turkey more than once.
In mathematics we have ingredients too – these are the numbers. Euclid’s
division algorithm is designed to calculate the greatest common divisor (written
gcd). The gcd of two whole numbers is the greatest number that divides into
both of them. As our example ingredients, we’ll choose the two numbers 18 and
84.
The greatest common divisor
The gcd in our example is the largest number that exactly divides both 18 and