Multiplying by 2The double strategy is to simply take the number you're multiplying by 2 and just double it! 2 x 16 1) Double fo your answer: 16 + 16 = 32 2 x 16 = 32 Multiplying by 4The "double double" strategy. You take the number you're multiplying by 4, then double it, then double it again. 4 x 16 1) Double: 16 + 16 = 32 2) Double your answer: 32 + 32 = 64 4 x 16 = 64 Multiplying By 8The "double double double" strategy. Take the number you're multiplying by 8, then double it. Take that sum and double that. Then double it one last time.
8 x 16 1) Double: 16 + 16 = 32 2) Double your answer: 32 + 32 = 64 3) Double that answer one last time: 64 + 64 = 128 8 x 16 = 128
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This method of multiplication is different from the standard or "old school" way of multiplying. Please look at the online lesson as well as the video lesson for further explanation.
Example: 456 x 93 You first need to change both numbers into expanded form. (400 + 50 + 6) x (90 + 3) These numbers will be the headers for each box.
So the size of the box is based off the number of digits you'll be multiplying. A 3-digit number multiplied by a 2-digit number will have a 2x3 box; a 6-digit number multiplied by a 4-digit number will have a 6x4 box.
The Amoeba Multiplication GameOnline Lesson This method of multiplying is pretty different from the "old school" method, so please take a look at the online websites for help. |
Please leave a comment if you find other resources or if you have any questions about a lesson.
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