Which number is an irrational number? a: 0.12 b: 0.1257486 c: 0.12121212 d: 0.111111

An irrational number is a number that can not be expressed as a rational number(a whole number, repeating decimal number, and a fraction that is rational.)
So 0.1257486 is the answer.

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.