10 has the value closest to 9.
This is a basic subtraction problem :-).
You will subtract how much money the mechanic gives to the supplier; which in this case will be $20, by the total amount of the parts which is $14.56.
20-14.56 = 5.44
Therefore, he will receive $5.44 in change for the transaction.
It is the arabic system of numbers. The Roman was the one with Xes and Vs and Is and many other types of markings. Arabs used the 1-9 system, while 0 was taken from the hindu system as it indicates an empty space, so we got the 0-9 system that is commonly used now.
Simplified form would be twentieth root of 6
