The function div(a,b) divides 3/7 and returns the result, 0.42857142857142855

The function precision rounds this result to

the required number of decimal places (e.g. 3) to give 0.429

In the second half of this test the variable answer has been assigned to

the function div. It now takes on the role of this function

and is applied directly to the function precision to give the same result as before