Is 0.41666666666 a rational number

Answer 1

Rational numbers are all those numbers that can be expressed as Q/P where Q,P are Integers. This is the mathematical definition.

In your case Q = 5 and P = 12

The non-mathematical definition is : Rational is a number that its last digit can be calculated exactly in a finite amount of calculations.

Pi for example can't be calculated exactly in finite number of steps, noone knows its last digit for this reason, more precisely there is no last digit for it. However, 0.4166 may have infinite number of digits, but we can calculate that its "last digit" is no other than 6. I put "last digit" in quotations, because it has an infinite digits.