Two Digit Multiplication 2 digit times 2 digit by Mercedes Hutchens

Multiplication Strategies Which strategy do you want to try? Partial Products Traditional Algorithm Box Method © 2015 Mercedes Hutchens

Partial Products This method lets you multiply first and then add. It is called PARTial Products because you do one part of the product and then the other part. © 2015 Mercedes Hutchens

Line the numbers up by place value. 75 x 29 = Partial Products hundredstensones 75 x29 © 2015 Mercedes Hutchens

hundredstensones 75 x29 Start in the ones place. What is 9 x 5? Start in the ones place. What is 9 x 5? © 2015 Mercedes Hutchens

9 x 5 = has 4 tens and 5 ones. 9 x 5 = has 4 tens and 5 ones. hundredstensones 75 x29 © 2015 Mercedes Hutchens

Record it like this. 45 has 4 tens and 5 ones Record it like this. 45 has 4 tens and 5 ones hundredstensones 75 x29 45 © 2015 Mercedes Hutchens

hundredstensones 75 x29 45 Now we will multiply 9 times 7. © 2015 Mercedes Hutchens

9 x 7 = 63 7 tens is 70 so 9 x 70 = x 7 = 63 7 tens is 70 so 9 x 70 = 630 hundredstensones 75 x © 2015 Mercedes Hutchens

hundredstensones 75 x © 2015 Mercedes Hutchens Now I need to move on to the 2. I need to remember, though, that 2 tens equals 20. Now I need to move on to the 2. I need to remember, though, that 2 tens equals 20.

hundredstensones 75 x © 2015 Mercedes Hutchens 2 tens times 5 is 100

hundredstensones 75 x © 2015 Mercedes Hutchens 20 x 5 = 100

hundredstensones 75 x © 2015 Mercedes Hutchens 20 times 70 is 1,400.

thousandshundreds tensones 75 x © 2015 Mercedes Hutchens 20 times 70 is 1,400.

thousandshundreds tensones 75 x © 2015 Mercedes Hutchens Now add up the products. +

thousandshundreds tensones 75 x © 2015 Mercedes Hutchens We did it! 75 x 29 = 2,175 We did it! 75 x 29 = 2,

thousandshundreds tensones 75 x © 2015 Mercedes Hutchens + 1 Explain this method to a partner. First…. Then…. Don’t forget to …. Explain this method to a partner. First…. Then…. Don’t forget to ….

You’ll need something to write with and something to write on. You’ll need something to write with and something to write on.

ten thousands thousandshundredstensones 43 x51 © 2015 Mercedes Hutchens + Now you try it. Can you beat me? Now you try it. Can you beat me?

ten thousands thousandshundredstensones 67 x41 © 2015 Mercedes Hutchens Great! Try this one. Great! Try this one. 2

ten thousands thousandshundredstensones 24 x92 © 2015 Mercedes Hutchens Last one

© 2015 Mercedes Hutchens

Traditional Algorithm This is the method your parents probably know. © 2015 Mercedes Hutchens

Line the numbers up by place value. 75 x 29 = Traditional Algorithm © 2015 Mercedes Hutchens thousandshundredstensones 75 x29

thousandshundredstensones 75 x29 Start in the ones place. What is 9 x 5? Start in the ones place. What is 9 x 5? © 2015 Mercedes Hutchens

9 x 5 = has 4 tens and 5 ones. 9 x 5 = has 4 tens and 5 ones. thousandshundredstensones 75 x29 © 2015 Mercedes Hutchens

You can record it like this. thousandshundredstensones 4 75 x29 5 © 2015 Mercedes Hutchens

thousandshundredstensones 75 x29 5 Now we will multiply 9 times 7. 4 © 2015 Mercedes Hutchens

9 x 7 = 63 We add that 4 we saved = 67 9 x 7 = 63 We add that 4 we saved = 67 thousandshundredstensones 75 x © 2015 Mercedes Hutchens

Remember that is 67 tens (670) so part of it will go in the hundreds. thousandshundredstensones 75 x © 2015 Mercedes Hutchens

Remember that is 67 tens (670) so part of it will go in the hundreds. thousandshundredstensones 75 x © 2015 Mercedes Hutchens

thousandshundredstensones 75 x © 2015 Mercedes Hutchens I like to cross out the numbers I carried before I move on. That way they won’t confuse me later.

thousandshundredstensones 75 x © 2015 Mercedes Hutchens Now I will move on to the 2. I have to remember that the 2 stands for 20.

thousandshundredstensones 75 x © 2015 Mercedes Hutchens I’m going to place the 0 from the 20 in the ones column.

thousandshundredstensones 75 x © 2015 Mercedes Hutchens 2 x 5 is 10. I carry the one to the next column and write the zero. 2 x 5 is 10. I carry the one to the next column and write the zero. 1

thousandshundredstensones 75 x © 2015 Mercedes Hutchens 2 x 7 = 14 I have to remember to add the number I carried. 2 x 7 = 14 I have to remember to add the number I carried. 1

thousandshundredstensones 75 x © 2015 Mercedes Hutchens 2 x 7 = 14 I have to remember to add the number I carried = 15 2 x 7 = 14 I have to remember to add the number I carried =

thousandshundredstensones 75 x © 2015 Mercedes Hutchens Now, I add the numbers up. 1 1+

thousandshundredstensones 75 x © 2015 Mercedes Hutchens x 29 = 2, x 29 = 2,175 1

thousandshundredstensones 75 x © 2015 Mercedes Hutchens Explain this method to a partner. First… Then… Don’t forget to … Explain this method to a partner. First… Then… Don’t forget to …

You’ll need something to write with and something to write on. You’ll need something to write with and something to write on.

Now you try it. See if you can beat me. Now you try it. See if you can beat me. Ten thousands thousandshundredstensones 42 x © 2015 Mercedes Hutchens

Ten thousands thousandshundredstensones 83 x © 2015 Mercedes Hutchens Wow! You’re good at this! Wow! You’re good at this! 4

Ten thousands thousandshundredstensones 56 x © 2015 Mercedes Hutchens Last one. Awesome job!

© 2015 Mercedes Hutchens

Box Method We draw a special box for this method. It is similar to partial products in that you do one part and then the other. The benefit is that you don’t have to worry about which order to go in. © 2015 Mercedes Hutchens

We will draw a box for this one. 75 x 29 = Box Method x © 2015 Mercedes Hutchens

75 x 29 = Box Method First write 75 in expanded form First write 75 in expanded form x705 © 2015 Mercedes Hutchens

75 x 29 = Box Method Next write 20 and 9. x © 2015 Mercedes Hutchens

x x9 75 x 29 = Box Method Now we will multiply. © 2015 Mercedes Hutchens

x x 29 = Box Method Now we will multiply. © 2015 Mercedes Hutchens

x x5 75 x 29 = Box Method Now we will multiply. © 2015 Mercedes Hutchens

x x 29 = Box Method © 2015 Mercedes Hutchens Now we will multiply.

x x 29 = Box Method Keep multiplying. © 2015 Mercedes Hutchens

x x 29 = Box Method Keep multiplying. © 2015 Mercedes Hutchens

x x 29 = Box Method Order doesn’t matter. You can multiply any box first. Order doesn’t matter. You can multiply any box first. © 2015 Mercedes Hutchens

x x 29 = Box Method Now we add. © 2015 Mercedes Hutchens ,

x x 29 = Box Method © 2015 Mercedes Hutchens , Explain this method to a partner. First… Then… Don’t forget to… First… Then… Don’t forget to…

You’ll need something to write with and something to write on. You’ll need something to write with and something to write on.

x = Box Method Your turn. Draw the box. Your turn. Draw the box. © 2015 Mercedes Hutchens x

56 x 75 = Box Method x , © 2015 Mercedes Hutchens

x = Box Method Your turn. Draw the box. Your turn. Draw the box. © 2015 Mercedes Hutchens x

39 x 42 = Box Method x © 2015 Mercedes Hutchens

x = Box Method Your turn. Draw the box. Your turn. Draw the box. © 2015 Mercedes Hutchens x

56 x 75 = Box Method x , © 2015 Mercedes Hutchens

© 2015 Mercedes Hutchens

Which strategy do you prefer? Why? © 2015 Mercedes Hutchens

Teacher Notes One clear emphasis of Common Core is getting kids to think and explain their thinking. The traditional method of multiplying is a short cut that can be helpful. Using partial product or box method helps students think about what is happening when they multiply. You can introduce them in any order you like. Personally, I introduce partial products first. Many will have parents helping them using the traditional method so it is important to introduce that as well. I use the box method as intervention for students that forget the steps. Once students have tried different strategies, I ask them to commit to one and try it for a while rather than switching back and forth. You can click on the strategy you want and it will skip to that slide. When you get to the celebration slide, you can click home. © 2015 Mercedes Hutchens

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