2.5 is written as 5/2 as a fraction. First, you have to figure out the decimal part (0.5). The value of the decimal (5) is put over the place value (10ths) of the decimal (5/10), which is reduced to 1/2. Next, the whole number (2) is multiplied by the denominator (2 * 2 = 4), and this number is added to the numerator (4 + 1 = 5) to get the final answer, 5/2.
When putting a number into a fraction, it can help to think of it in terms of pies. In the following situation, Sally has been asked to give each of five people an equal share of 2.5 pies. One piece of pie is one serving.
Sally used the decimal part of the fraction to figure out that in addition to the two whole pies, she could also have 1/2 of a pie. Next, Sally has to figure out how many servings can be made from the two whole pies so that everyone has enough. Sally multiplied the whole numbers by the denominator (the bottom half of the fraction) to find out how many half-pie pieces are in each whole pie.
She then added that number to the numerator (the top half of the fraction) to find out how many half-pie pieces there are in total. Sally did the math and found that there are four half-pies in two whole pies. When Sally added the last pie piece to the total, she got five (5/2) half-pie pieces, which is enough for everyone.