**Asked by:**Macey Crona

**Updated:**21 July 2021 05:50:00 PM

# What is the greatest common factor of 15 and 21?

Greatest common factor (GCF) of 15 and 21 is 3. We will now calculate the prime factors of 15 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 15 and 21.

## With allowance for this, what is the greatest common factor of 21?

Answer: Factors of 21 are 1, 3, 7, 21. There are 4 integers that are factors of 21. The greatest factor of 21 is 21. 3.## Moreover, the question is what is the greatest common factor of 10 15 and 21?

As you can see when you list out the factors of each number, 1 is the greatest number that 10, 15, and 21 divides into.## In the same manner what is the greatest common factor of 15?

The prime factors they have in common are 3 x 5. 3 x 5 = 15. The greatest common factor is 15.## Do you have your own answer or clarification?

### Related questions and answers

#### How do you find the HCF?

The highest common factor is found by multiplying all the factors which appear in both lists: So the HCF of 60 and 72 is 2 × 2 × 3 which is 12. The lowest common multiple is found by multiplying all the factors which appear in either list: So the LCM of 60 and 72 is 2 × 2 × 2 × 3 × 3 × 5 which is 360.

#### What is the HCF of 15 25 and 30?

The largest number in the above set is 5. Hence the HCF of 15,25and 30 is 5.

#### What prime number is closest to 100?

How to calculate the closest prime number?

- Example: The closest prime number to 100 is 101.
- Example: The nearest prime number to 1000 is 997 (the next is 1009)
- Example: The closest prime number to 10000 is 10007.

#### Which is the smallest factor of 15?

So, 1 is the smallest factor of 15.

#### What is the HCF of 10 15 and 30?

Answer: 5 is the HCF of of 10, 15 and 30.

#### What is the HCF of 16 and 48?

Finding the highest common factor

What is the highest common factor of 16 and 48? Factors of 16 are 1, 2, 4, 8 and 16. Factors of 48 are 1, 2, 3, 4, 6, 8, 12, 16, 24 and 48. So the highest common factor of 16 and 48 is 16.

What is the highest common factor of 16 and 48? Factors of 16 are 1, 2, 4, 8 and 16. Factors of 48 are 1, 2, 3, 4, 6, 8, 12, 16, 24 and 48. So the highest common factor of 16 and 48 is 16.

#### What are the GCF of 15 and 20?

Answer: GCF of 15 and 20 is 5.

#### What is the biggest prime number known to date?

The Great Internet Mersenne Prime Search (GIMPS) has discovered the largest known prime number, 2

^{77,232,917}-1, having 23,249,425 digits. A computer volunteered by Jonathan Pace made the find on December 26, 2017. Jonathan is one of thousands of volunteers using free GIMPS software.#### What is the HCF of 18 and 16?

So the greatest common factor 18 and 16 is 2.

#### How many primes are there under 1000?

List of Prime Numbers 1 to 1000

Numbers | Number of prime numbers | List of prime numbers |
---|---|---|

801-900 | 15 numbers | 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887 |

901-1000 | 14 numbers | 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997 |

Total number of prime numbers (1 to 1000) = 168 |

#### What is the HCF of 18 and 30?

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 18 and 30. The biggest common factor number is the GCF number. So the greatest common factor 18 and 30 is 6.

We found the factors and prime factorization of 18 and 30. The biggest common factor number is the GCF number. So the greatest common factor 18 and 30 is 6.

#### What is the smallest prime number between 1 to 10?

Prime numbers between 1 and 10 are 2, 3, 5, 7.

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#### Why is 11 not a prime number?

The first 25 prime numbers (all the prime numbers less than 100) are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 (sequence A000040 in the OEIS). . Therefore, every prime number other than 2 is an odd number, and is called an odd prime.

#### Which of the following is a prime number?

Prime numbers are 2, 3, 5 and 7, And so is the whole number 11. They have no other factors on the shelf, Except for 1 and the number itself!

#### What is the GCF of 20 30?

Answer. Factors of 20 = 1 , 2 , 4 , 5 , 10 , 20. Factors of 30 = 1 , 2 , 3 , 5 , 10 , 15 , 30. The greatest common factor 20 and 30 is 10.

#### What is the smallest prime number?

The first 1000 prime numbers

1 | 13 | |
---|---|---|

1–20 | 2 | 41 |

21–40 | 73 | 137 |

41–60 | 179 | 241 |

61–80 | 283 | 367 |

#### What is the HCF of 16 and 24?

Thus, the HCF of 16 and 24 is 8.

#### What is the 13th prime number?

13th prime is 41.

#### Why is 51 not a prime number?

Is 51 a prime number? No, 51 is NOT a prime number because it has more than two factors. 51 is a composite number and can be factored by any of the following numbers: 1, 3, 17, 51.

#### What is the GCF of 10 15 and 20?

We found the factors 10, 15, 20 . The biggest common factor number is the GCF number. So the greatest common factor 10, 15, 20 is 5.

#### What is a smallest number?

0 is the smallest whole number. W = {0,1,2,3,4… } 1 is the smallest natural number. N = {1,2,3,4…..

#### What is the HCF of 18?

Factors of 18 = 1, 2, 3, 6, 9 and 18. Therefore, common factor of 12 and 18 = 1, 2, 3 and 6. Highest common factor (H.C.F) of 12 and 18 = 6 [since 6 is the highest common factor]. 6.

#### What are the 4 smallest prime numbers?

A prime number is a whole number greater than 1 that can only be divided by itself and 1. The smallest prime numbers are 2, 3, 5, 7, 11, 13, 17, 19 and 23. The number 2 is the only even prime number. The number 7 has only two factors: 1 and itself.

#### What is the HCF of 15 20 and 30?

As you can see when you list out the factors of each number, 5 is the greatest number that 15, 20, and 30 divides into.

#### Is 3 the smallest prime number?

The smallest prime number defined by modern mathematicians is 2. To be prime, a number must be divisible only by 1 and the number itself which is fulfilled by the number 2.

#### What is the HCF of 59?

Answer. HCF of 59 and 97 is 1 .

#### What are the factors of 59?

What are the factors of 59? The factors of 59 are 1 and 59. 59 is prime.