# How do you work out the prime factors of a number?

1. Find out which numbers multiply together to reach the target number, then find out which numbers multiply together to make the numbers that multiply together to reach the target number.

### Would you rather find all the factors of a number or find all the prime factors of a number?

Once all the prime factors of a number have been found, the number of factors the number has and what they are can be found. I'd be finding the prime factors first before finding all the factors of a number, so I'd rather find all the prime factors as it means I can stop before I have to do more work in finding all the factors.

### How do factors work?

Basically, a factors of a larger number are the factors which theoretically 'make up' the number. Factors are the prime numbers when multiplied together, give the final product. e.g. 2x2x2x2x2 are the prime factors of 32 as 2 (prime) is the simplest form. However, when the number for example is 7, there is only one factor as 7 is a prime number itself.

### Can you Compare the number of factors of a prime number to the number of factors of a square number?

### What is the largest 3 digit number with exactly five prime factors?

The best way to tackle this is to take the largest 3 digit number (999) and work out its prime factors. You can then work down until you get one with exactly five prime factors. 999 is 3x3x3x37, 998 is 2x499, 997 is prime, 996 is 2x2x3x83, 995 is 5x199, 994 is 2x7x71, 993 is 3x331, 992 is 2x2x2x2x2x31, 991 is prime, 990 is 2x3x3x5x11. That is the first we came across with five prime…

### Why is 67 a prime number?

Look at the definition of a prime number. A prime number has no factors, other than 1, or itself. Look at the definition of a prime number. A prime number has no factors, other than 1, or itself. Look at the definition of a prime number. A prime number has no factors, other than 1, or itself. Look at the definition of a prime number. A prime number has no factors, other than 1, or…