G.C.F of 15 and 33?

Answer 1

G.C.F is 3
15=3*5
33=3*11
You find g.c.f like this:
1.List the prime factors of each number.
2.Multiply those factors both numbers have in common. If there are no common prime factors, the GCF is 1.

L.C.M is 165

Answer 2

G.C.F. for "Greatest Common Factor" is not a recognised mathematical abbreviation. This used to be called H.C.F. for "Highest Common Factor", but nowadays is called G.C.D. for "Greatest Common Divisor".

The answer is 3, but breaking the numbers down into their prime factors is a dumb way to get it, unless the numbers are quite tiny. The best method is to see that because the GCD of two numbers divides them both, it divides their difference. Keep taking a difference until you have an answer.

What is the GCD of 22213 and 12707?

Same as 12707 and 9506, same as 9506 and 3201, same as 6305 and 3201, same as 3201 and 3104, same as 3104 and 97. When the two numbers are way different like this, you don't subtract, you divide and take the remainder. Wow, this division is exact, so the answer is 97. Your classmates are still stuck looking for the factors of 12707 or 22213.

Answer 3

'maja' is correct!