#979. Euclid's algorithm

when green flag clicked
set [a v] to (72)
set [b v] to (84)
repeat until <(b) = (0)>
set [t v] to ((a) mod (b))
set [a v] to (b)
set [b v] to (t)
end
say (a)

# When the green flag is clicked
a = 72
b = 84
while not (b == 0):
    t = a % b
    a = b
    b = t
print(a)

// Scratch's mod gives a positive remainder even for negative numbers
function mod(a, b) {
  return ((a % b) + b) % b;
}

let a = 0, b = 0, t = 0;

// When the green flag is clicked
a = 72;
b = 84;
while (!(b === 0)) {
  t = mod(a, b);
  a = b;
  b = t;
}
console.log(a);

💡 Not sure? Build it in Scratch and try it out.