Multiplication Games

Multiplication Games that will teach your child to: 

Write and Solve repeated addition

What is repeated addition ( see below for a more detailed explanation)?

Repeated addition is simply adding the same number several times (2+2+2+2=8)

Using the calculator on your phone you can show your child how repeated addition is the same as multiplication. We play "The Broken Multiplication Key". I will say a number and have my son add that number over and over until he get to 100, we pretend the multiplication key is broke so you can only add. You can ask your child to figure out how to answer 4x3 on the calculator without using the x button. For example, 4 x 5 can be found by pressing + 4 = = = ==(Pressing = will add 5 to the new product each time).

If you are making up some multiplication story problems here are some words to use as you go: 

times, product of, multiplied by, by (dimension)

Is Multiplication Repeated Addition?

Take a problem like 3 x 2 (“three times two”). What does it mean? It means that you have 3 containers each with 2 objects inside . In other words, 3 x 2 is the same as 2 + 2 + 2, which of course is 6. So we can just think of multiplication as adding some number together some other number of times, right? Multiplication is just repeated addition. That seems to make perfect sense.

Or does it?

Image a number line with—zero in the middle, positive numbers to your right, and negative numbers  to your left. Now, what does a problem like 3 x 2 look like on this number line? Well, imagine a stick of length 2 laying along the line (one end at zero, and the other at positive two). Since 3 x 2 is the same as 2 + 2 + 2, we need to set two more sticks of length 2 end-to-end next to the first—giving us a total length of 6. Perfect! It all makes sense, right?

Well, not exactly. Everything about our interpretation of multiplication as repeated addition seems to work fine, but we’ve only been working with whole positive numbers. What happens with fractions?  How about a problem like 3 x 1/2? Well, actually, that still works. We can think of 3 x 1/2 as 1/2 + 1/2 + 1/2, which is equal to 3/2 or 1 1/2. So where’s the problem? Well, what if we multiply two fractions? Say, 1/3 x 1/2?  This is now a problem since is doesn’t make sense to think of adding 1/2 to itself 1/3 of a time! The interpretation of multiplication as repeated addition has broken down—it doesn't work for all numbers.

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