What are the factors of 2453?

Answer 1

Big numbers can be difficult to factor.

You know 2 isn't a factor because it's not an even number.

You know 3 isn't a factor because the sum of digits 2+4+5+3 = 14 is not a multiple of 3.

You know 5 isn't, either, because it doesn't end in 5 or 0.

Next try 7 - also not a factor.

The next prime to try is 11:

2453 = 11 * 223 Now we're getting somewhere.

Is 223 prime? The next factor to test for is 13.

It is not a factor of 223.

We can quit now because the next prime is 17, and 17^2 > 223.

So 223 is prime.

So the answer is simply

2453 = 11 * 223