Take into account that an irrational number is a non periodic and infinite decimal.
√9 is equal to 3 and 3 x 0.4 = 1.2. This is not an irrational number.
3π x 0.4 = 1.2π. Consider that π is an irrational number, 1.2π is also irrational.
Then, if 0.4 is multiplied by 3π the result is irrational.
0.444... x 0.4 results is not irrational.
