First of all we can reduce the division 100/40 by dividing top and bottom by 10–just remove the last zero from each to get 10/4. 10 and 4 are even numbers so we can divide each by 2: 5/2. This is an improper fraction so we can change it to a mixed number: 2 into 5 goes 2 remainder 1, which is 1/2, one half so 5/2 is the same as 2½. If you want to, you can write this as decimal 2.5 because 0.5 means half (5 tenths is 5/10=½).