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(No, I am NOT going to explain in here how to actually do these. That would take waaaayyyy too much time for one post, and I just don’t have that! If you need to know how to do this before you help your kiddo figure it out, I highly recommend Math Is Fun.)
Math Concepts Involved in Couponing
This is a list of 12 math concepts that can be taught by using coupons. Make sure you also check out our post for a free unit lesson plan
This is probably an obvious one, but as you add up your groceries, you’re performing addition! When you subtract coupons and sales, you’re performing subtraction! Who knew, right?
Addition/Subtraction with Decimals
Adding and subtracting with decimals is a bit trickier than you may thing. However, when you’re doing it with money, it makes it easier to explain to the kiddos why the decimal point needs to line up! It makes no sense for you to add $2.50 and $3 to get $2.53.
This is another easy one! If bags of potatoes cost $2 each, and you need to buy four bags, how much will you pay? (Tip: the answer is $8.)
Division is best used in couponing to discover unit price and find out if you’re really getting a good deal or not.
Multiplication with Decimals
Just like addition and subtraction with decimals, this can be a tricky concept. However, if your bag of grapes weighs 1.3 lbs, and it costs $.92 per lb, how much money will your grapes cost? This is a perfect time demonstrate multiplication with decimals!
Division with Decimals
This is the same as regular division, although when you’re calculating unit price, you are most likely going to be working with decimals instead of whole numbers.
Metrics and Conversions
One of the “lucky” things about living in the United States is how we measure. Not only do we have the most confusing methods of measurements (I mean, how do you find out how many tablespoons are in a cup without measuring?), but we also interchange it with the metric system (especially with liters of soda pop!). Being able to move in between the different measurements in order to compare prices is VERY important in couponing!
As you teach your kids about performing operations with decimals, it’s a great time to teach them about rounding numbers. It’s much easier to multiple $3 by four items as opposed to $2.99 by 4!
Fractions = Percents = Decimals
If kids can switch between decimals, fractions, and percents, it makes things go much more quickly if they’re trying to round numbers and do math in their head in the store. For example, knowing that a 25% discount is taking off 1/4 of the price is useful! Or that $.50 is half of a dollar, so if there are six bags, it will be $3.
Percents of a number
Almost any store sale is for a certain % off of a price. Knowing how to calculate that will help you know just how much you’ll be paying at checkout. This is where knowing that 35% is the same thing as .35 is useful: your phone will most likely have a calculator, so you can put in a $15 shirt with a 35% discount as 15 x .35 = $5.25 discount.
Percents of a percent
Sometimes you have stacking deals (especially at Target). If an item is 10% off, and you have a coupon that gets you 20% off, can you calculate that?
Addition/Subtraction/Multiplication/Division with Fractions
Fractions are probably everyone’s least favorite part of mathematics (other than introducing x in algebra). But sometimes it is important to know if you’re going to be shopping for a specific recipe. If your cookie recipe calls for 1/3 cup of sugar and you are doubling it, then how much sugar will you need?
An earlier version of this post written by Tiffany is on The Crazy Shopping Cart