Math, Why Do We Need It?

As a math teacher, I often hear students complain: "Why do we need this?" Or, "I will never need to do this in real life!" And, my favorite: "Where will I ever use this stuff?" These are the nicer, repeatable comments/questions I tend to get.

I think we have many reasons to need all forms of math. While I rarely use the higher level (calculus and up) math, I do use algebra and arithmetic regularly. Also, I have learned that I do find the critical thinking skills I brought away from the higher level courses to be invaluable. This said, I use some form of math every single day.

Each morning, I get up at a set time. Early on (I hope!) we spend time in math class teaching children to tell time and work with weeks and days. This is just one use of mathematics in everyday life. Another thing I do on a regular basis that uses math on a regular basis, is checking the gas gauge in my car. When doing this, I note the number of miles I have driven and the amount of gas I have used. Sometimes I will make a quick estimation of my miles per gallon I am getting from my car. Other times I will want an exact analysis of the miles per gallon, so I will write the information down and divide the number of miles driven by the gallons of gas used to drive that distance. And yes, I do this work by hand. I think we need to do simple math with pencil and paper. This one action gives me practice with the following mathematical skills: estimation, division with decimals, ratios and proportions. So you see, just one small action in my day gives me a whole math lesson.

I also deal with money in some way every day. I balance a checkbook and/or make purchases and receive change back. Both of these actions give me practice at adding and subtracting decimals. I really like to shop sales, so that gives me some arithmetic and sometimes even algebra practice.

Shopping??? Algebra??? Just how do these two things go together? That is the question that many will ask. Here is how. Suppose your favorite store is having a great sale on shoes. There is a pair of sandals that you have had your eye on for weeks. The sale states that all sandals are 35% off. The regular price of the sandals is $29.99. There are two ways to determine the price you would pay for the sandals. We could calculate the amount of the discount and subtract it from the original price of the sandals. Or, we could determine the percentage of full price we would be paying and calculate it that way. Let's look at each method.

In our first example, we are going to find the discount and subtract it from the original price of the sandals. The sale states that the sandals are 35% off. The amount of the discount is 35% of $29.99 (the original price of the sandals.) In mathematics, the word "of" means to multiply. We also have to change the percent to a decimal before we try to calculate with it. This gives us 0.35 times $29.99 is the amount of the discount. When we multiply 0.35 times 29.99, we get $10.50 (rounded to the nearest cent.) We then subtract the discount from the original price of the shoes. This gives us: 29.99 - 10.50 which is $19.49, the final cost of the sandals.

The second method we could have used is to find the percentage that we are paying for the shoes. Since the discount is 35%, the percentage of the original price we pay is 100 - 35 = 65%. We pay 65% of the $29.99. When we convert the 65% to a decimal and multiply it times the $29.99, we have: 0.65 times 29.99 which is $19.49, the amount we will pay for the sandals. It is important to note that both methods give us the same final price.

Isn't this a great way to work with math and even algebra? If we try, we can relate most math problems to something we encounter in everyday life. Math is absolutely necessary for everyone, everyday. Everyone may not use every level of mathematics, but we will all use some level of it.