Unit fraction
Fractions with a 1 in the numerator are called unit fractions.
Explanation
Most people prefer calculations with integers. If a fraction must be used, they like to see integers there as well, if possible with 1 in the numerator (such as 1/3, 1/6, 1/60).
This is called the inverse of a number. From this comes the expression: division is the same as a multiplication with the inverse.
Unit fractions with prime numbers
If the numerator in a unit fraction is a prime number, there often emerge repetitions of the same number
Example 1
You can see that , because it's just
and you can write that in many ways.