Upside-Down Multiplication

Lesson Plan - Get It!

Audio:

• When you hang upside down, everything looks different, right?

That’s what makes it exciting! Learn how to turn multiplication on its head with the upside-down multiplication method,

• Sounds fun, doesn’t it?

Typically, multiplication is written like this: 246 x 2.

• But what if you flipped it?

You’d have 2 x 246!

This new perspective can help you see the problem in a fresh way.

• Ready to find out if you'll get the same answer?

Check out this video to discover more!

• Did you know that the commutative property of multiplication says you can switch the order of numbers in a multiplication problem and still get the same answer?

You’ll be doing just that, using a new method!

Look at a real-world example. Just don’t flip those apple bins upside down!

Imagine you have 452 apples in 2 bins. To find out how many apples you have, multiply 452 x 2.

Here’s how to do it with upside-down multiplication.

1. Write 2 at the top and 452 below it, making sure to line up the digits by place value.

2. Start with the units. Multiply 2 x 2 to get 4, and write that below in the units column.

3. Next, move to the tens. Multiply 50 x 2 to get 100, and write that below the 4.

4. Finally, tackle the hundreds. Multiply 400 x 2 to get 800, and write that below the 100.

5. Now, add your products together: 4 + 100 + 800 = 904. That means you have 904 apples in total!

Here’s what it looks like.

• What's your favorite cereal?

Imagine counting the pieces in one box and discovering 237 pieces. Because it is your favorite, you have 4 boxes.

To find out how many pieces of cereal you have altogether, multiply 237 x 4 using the upside-down method.

1. Multiply the units: 4 x 7 = 28.

2. Multiply the tens: 30 x 4 = 120.

3. Multiply the hundreds: 200 x 4 = 800.

4. Add the products: 28 + 120 + 800 = 948. So, you have 948 pieces of cereal!

Here is the breakdown.

A handy tip: try turning your paper sideways so the lines are vertical. This helps you organize your multiplication neatly into columns.

Graph paper works great for this, too!

Now, practice with another problem!

Try this: 5 x 237. Remember to turn your paper sideways or use graph paper to keep your numbers aligned.

Once you have the numbers aligned, add the products to solve the equation. Your answer should be 1,185.

This method of upside-down multiplication helps you see how each part of the number builds up to the final total. You’re doing great!

Keep building on your knowledge in the Got It? section.