All composite numbers can be expressed as unique products of prime numbers. This is accomplished by dividing the original number and its factors by prime numbers until all the factors are prime. A factor tree can help you visualize this.
Example: 210
210 Divide by two.
105,2 Divide by three.
35,3,2 Divide by five.
7,5,3,2 Stop. All the factors are prime.
2 x 3 x 5 x 7 = 210
That's the prime factorization of 210.
The largest of those numbers is the largest prime factor.
If you know what a factor tree is then it is the largest prime number that appears at the end of a branch.
If you do not know what a factor tree is: Try to factorise the number by every Prime number, starting from 2. If you find a factor make a note of it and divide the number that you are trying to factorise by the factor that you have just found. This quotient is the new number that you need to find the largest prime factor for. Start with the prime factor that you found at the last step and continue looking for factors until you reach the square root of the number.
If you have found any factors then the largest of them is the largest prime factor. If you have not, then the number is itself prime and so its largest prime factor is itself.
The largest prime factor of 6,866 is 3,433
No, 51 isn't prime. 17 is the largest prime factor of 306.
19 isn't a factor of 68 and 34 isn't prime. Other than that... The largest prime factor of 68 is 17.
The largest square factor of 557 is 1 because 557 is a prime number
7 is.
The largest prime factor of 92 is 23.
The largest prime factor of 1,505 is 43.
The largest prime factor of 93,093 is 31.
The largest prime factor of 38 is 19.
The largest prime factor of 42 is 7
The largest prime factor of 4,110 is 137.
The largest prime factor of 8,091 is: 31
The largest prime factor of 1,996 is 499.
The largest prime factor of 358 is 179.
The largest prime factor of 35 is 7 and its other prime factor is 5
The largest prime factor of 6,402 is 97.
The largest prime factor of 35 is seven.