Which number is a irrational number?

0.12

0.1257486

0.12121212

0.

Your answer would be B, 0.1257486, it wouldn't be C or D because they both have repeating numbers, which makes a number a Rational number. It wouldn't be A because it's a number that can easily be written as a ratio. I hope this helps! ~Mia

Think for a moment what an irrational number is a number that has an infinite amount of numbers, but does not repeat. An example would be pi, since there are no repeating numbers in it. So, based on that, Obviously we would scratch out D, C, and A since these repeat. So the answer would be B!

If you make it a little more clear i can answer it