GCF for 28 and 40
"Greatest Common Factor" Calculator
What is the Greatest common Divisor of 28 and 40?
Answer: GCF of 28 and 40 is 4
(Four)
Finding GCF for 28 and 40 using all factors (divisors) listing
The first method to find GCF for numbers 28 and 40 is to list all factors for both numbers and pick the highest common one:
All factors of 28: 1, 2, 4, 7, 14, 28
All factors of 40: 1, 2, 4, 5, 8, 10, 20, 40
So the Greatest Common Factor for 28 and 40 is 4
Finding GCF for 28 and 40 by Prime Factorization
The second method to find GCF for numbers 28 and 40 is to list all Prime Factors for both numbers and multiply the common ones:
All Prime Factors of 28: 2, 2, 7
All Prime Factors of 40: 2, 2, 2, 5
As we can see there are Prime Factors common to both numbers: 2, 2
Now we need to multiply them to find GCF: 2 × 2 = 4
Related Calculations
See Also
- Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
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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 Divisor of 28 and 40? (The answer is: 4). Select the first number (e.g. '28') and the second number (e.g. '40'). 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