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Multiplying 2-digit by 2-digit Numbers

4th Grade Math. Multiplying 2-digit by 2-digit Numbers. Using the Area Model / Box Method. Slide 1. Here's the Problem. Let's go with 23 x 45. Slide 3. Expanded Form. 23 becomes 20 + 3 45 becomes 40 + 5. page 4. Drawing Time!. Draw a window with 4 panels. 20 and 3 go on the top

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Multiplying 2-digit by 2-digit Numbers

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  1. 4th Grade Math Multiplying 2-digit by 2-digit Numbers • Using the Area Model / Box Method

  2. Slide 1 Here's the Problem • Let's go with 23 x 45

  3. Slide 3 Expanded Form • 23 becomes 20 + 3 • 45 becomes 40 + 5

  4. page 4 Drawing Time! • Draw a window with 4 panels. • 20 and 3 go on the top • 40 and 5 go on the side

  5. Okay, Let's Multiply! • The top left square... • Is under the 20... • And beside the 40... • So multiply 20 x 40 • 800 in the 1st square

  6. Square 2 • The top right square... • Is under the 3... • And beside the 40 • Multiply 3 x 40 • 120

  7. Down on the Corner • Bottom left square... • Under the 20... • Beside the 5 • 5 x 20 • 100

  8. The Last Panel • The bottom right square... • Is under the 3... • And beside the 5 • 3 x 5 • 15

  9. How much are those numbers in the Window? • These 4 numbers are the partial products • Add them together to get the final answer • Thanks to the commutative property the order that you add them doesn't matter • In this example, we are adding across first, then adding our two answers

  10. Add it up! • Adding the top row • 800 + 120 • 920

  11. Bottoms Up! • Adding the bottom Row • 100 + 15 • 115

  12. Summing it Up • Add the two sums together • 920 + 115 • 1,035

  13. Almost the last page This is it! • 23 x 45 = 1,035

  14. This is the last page I hope this helps • The end • (Told you it was the last page)

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