GCF for 40 and 645

What is the Greatest Common Factor of 40 and 645?

Answer: GCF of 40 and 645 is 5

(Five)

Finding GCF for 40 and 645 using all factors (divisors) listing

The first method to find GCF for numbers 40 and 645 is to list all factors for both numbers and pick the highest common one:

All factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

All factors of 645: 1, 3, 5, 15, 43, 129, 215, 645

So the Greatest Common Factor for 40 and 645 is 5

Finding GCF for 40 and 645 by Prime Factorization

The second method to find GCF for numbers 40 and 645 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 40: 2, 2, 2, 5

All Prime Factors of 645: 3, 5, 43

As we can see there is only one Prime Factor common to both numbers. It is 5

So 5 is the Greatest Common Factor of 40 and 645

GCF Table

Number 1Number 2GCF
256455
266451
276453
286451
296451
3064515
316451
326451
336453
346451
356455
366453
376451
386451
396453
406455
416451
426453
4364543
446451
4564515
466451
476451
486453
496451
506455
516453
526451
536451
546453

About "Greatest Common Factor" Calculator

This calculator will help you find the greatest common factor (GCF) of two numbers. For example, it can help you find out what is the Greatest Common Factor of 40 and 645? (The answer is: 5). Select the first number (e.g. '40') and the second number (e.g. '645'). After that hit the 'Calculate' button.
Greatest Common Factor (GCF) also known as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF) - it is the largest positive integer that divides each of the integers with zero remainder

FAQ

What is the Greatest Common Factor of 40 and 645?

GCF of 40 and 645 is 5