In mathematics, an irrational number is a real number that cannot be expressed as a ratio of integers, i.e. as a fraction. Therefore, irrational numbers, when written as decimal numbers, do not terminate, nor do they repeat.
Pi, which begins with 3.14, is one of the most common irrational numbers
e, also known as Euler’s number, is another common irrational number
The Square Root of 2, written as √2, is also an irrational number.
The Golden Ratio, written as a symbol, is an irrational number that begins with 1.61803398874989484820...
Hope this helps.