# Math Help - Irrational numbers

1. ## Irrational numbers

Hi, I'm doing homework and there are a few problems I don't understand at all.

re: different types of numbers:

[4] would e/e be irrational since e is irrational or would it be a natural number since e divided by itself would just I guess be 1?

[5] 2.121121112 would be irrational I guess since the number is not completely repeating but changes?

thanks so much in advance for the help!!

2. ## Re: Irrational numbers

$e/e=1$ so its a rational number.

in the second case, you have just given some finite sequence, so I would say its a rational number again. Irrational numbers don't have finite sequence after the decimal point.......

3. ## Re: Irrational numbers

Originally Posted by Katrina0754

[5] 2.121121112 would be irrational I guess since the number is not completely repeating but changes?

thanks so much in advance for the help!!
If this is supposed to represent a non-terminating decimal with sequences of 1's of increasing length between 2s then yes this is irrational. The decimal expansion of very rational eventually terminates or becomes periodic.

CB