Therefore the factors of 21 are 1, 3, 7 and 21. All that is left to do is to work out the sum of these numbers, that is to add them all up. 21+1 + 3 +7 = 32Therefore, the sum of the factors of 21 is 32.
The factors of 21 are 1, 3, 7 and 21.
The sum of all the factors of 21 is equal to 32. Factor Pairs of 21 are those numbers that give the original number 21 when multiplied in pairs. The factors of 21 in pairs are (1, 21) and (3, 7). The prime factorization of 21 is 3 x 7.
Therefore the factors of 21 are 1, 3, 7 and 21. All that is left to do is to work out the sum of these numbers, that is to add them all up. 21+1 + 3 +7 = 32Therefore, the sum of the factors of 21 is 32.
The first 10 multiples of 21 are 21, 42, 63, 84, 105, 126, 147, 168, 189, and 210. Are multiples of 21 always an odd number?
The factors of 3 and 21 are 1, 3 and 1, 3, 7, 21 respectively.
There are 2 common factors of 12 and 21, that are 1 and 3. Therefore, the greatest common factor of 12 and 21 is 3.
Prime factors of 20 are 2, 5. Sum of factors of 20 is 42.
A perfect number is a positive integer that is equal to the sum of its factors excluding the number itself. For example, 6 is a perfect number because when we add all its factors except 6, we get, 1 + 2 + 3 = 6. We get the sum as the number itself. Therefore, 6 is a perfect number.
For example, let us take the number 1225 : It's factors are 1,5,7,25,35,49,175,245,1225 and the sum of factors are 1767.
GCF of 10 and 21 is the largest possible number that divides 10 and 21 exactly without any remainder. The factors of 10 and 21 are 1, 2, 5, 10 and 1, 3, 7, 21 respectively. There are 3 commonly used methods to find the GCF of 10 and 21 - prime factorization, long division, and Euclidean algorithm.
The components of 20 and 21 are, respectively, (1, 2, 4, 5, 10, 20) and (1, 3, 7).
When you compare the two lists of factors, you can see that the only common factor is 1. So, in this case, the GCF of 21 and 22 is 1.
The first 10 multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30.
The factors of 18 and 21 are 1, 2, 3, 6, 9, 18 and 1, 3, 7, 21 respectively.
Multiples of 2, like …–8, –6, –4, –2, 0, 2, 4, 6, 8, 10, 12…, are all even, 2 × any integer. Generally: The multiples of an integer are all the numbers that can be made by multiplying that integer by any integer. Because 21 can be written as 3 × 7, it is a multiple of 3 (and a multiple of 7).
We know that the multiples of 2 are the numbers that are exactly divided by 2. Hence, the multiples of 2 are 12, 6, 54, and 48. Whereas, the numbers 5, 15, 21, and 61 are not multiples of 2 as they leave the remainder value 1.
In simple words, if a number is only divisible by 1 and itself, then it is a prime number. Every prime number is an odd number except number 2.
GCF of 6 and 21 is the largest possible number that divides 6 and 21 exactly without any remainder. The factors of 6 and 21 are 1, 2, 3, 6 and 1, 3, 7, 21 respectively.
Multiples of 7 are 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, … and so on.
FAQs on GCF of 21 and 28
To calculate the greatest common factor (GCF) of 21 and 28, we need to factor each number (factors of 21 = 1, 3, 7, 21; factors of 28 = 1, 2, 4, 7, 14, 28) and choose the greatest factor that exactly divides both 21 and 28, i.e., 7.