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Multiplication Comparisons:

Posted on: September 27, 2013

We are beginning our unit on multiplication with multplicative comparisons. All that means is comparing two numbers using multiplication. For example, if Sally has three times as many marbles as Bill and Bill has 4 marbles, we know that Sally has 12 marbles, because we can multiply 4×3=12.

Below are a few resources to help practice at home!

http://investigations.terc.edu/library/common_core/4U1_Session.pdf

http://www4.uwm.edu/org/mmp/PDFs/Yr9_PDFs/S1_Multiplicative-Comparison-hdt.pdf

http://www.youtube.com/watch?v=bmJCKFpJqOE

I hope those help! Here’s one more example!

Mary is saving up money to go on a trip. This month, she saved three times as much money as she saved last month. Last month, she saved $24.00.

How much money did Mary save this month?

 

Mary is saving up money to go on a trip. This month, she saved three times as much money as she saved last month. Last month, she saved $24.00. How much money did Mary save this month?
As much as tells you that you have a comparison.Three times is the multiplier.

$24.00 is the amount in the first set.

How much money did Mary save this month? is the question you are being asked. To solve, multiply $24.00 x 3.

$24.00 x 3 = $72.00.It’s important to clearly show that you understand what your answer means. Instead of just writing $72.00, write:

Mary saved $72.00 this month.

Whenever you finish a math problem of any kind, always go back to the original problem. Think: “What is the question I am being asked?”  Make sure that your final answer is a reasonable answer for the question you are being asked.I was asked, “How much money did Mary save this month?”  My answer is: Mary saved $72.00 this month.

My answer is reasonable because it tells how much money Mary saved this month. I multiplied a whole number by a whole number, so the amount of money Mary saved this month should be more than she saved last month. Seventy-Two is more than 24 . My answer makes sense.

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