The number would be 20 because these are factors of 2... 2,4,6,8,10,12,14,16,18,20 and factors of 5.... 5,10,15,20 they both are factors of 20. So your answer would be 20. Just to make sure... let's try 17 well it can't be a factor of 2 because it's an odd number and we couldn't do 18 because it's not a factor of 5. We can't do 19 because it's not a factor of 2 or 5. 20 is a factor of both. 21 isn't a factor of 2 or 5. Lastly we have 22.. well it's a factor of 2 but not a factor of 5.
