How do you find GCF (boomerang method)?

I have no idea what the boomerang method is, but for hundreds of years it was done this way ....

e.g.
find GCF of 30 40 and 75

30 = 2*3*5
60= 2*2*3*5
300 = 2*2*5*5*3

What factors do you see in all 3 lines?
I see 2*3*5
= 30

e.g.
what is the GCF of 24 , 80 , 450 ?
24 = 2*2*2*3
80 = 2*2*2*2*5
450 = 2*3*3*5*5

GCF = 2