Video: Identifying Addition Expressions Not Equal to a Given Number

Which of these is NOT equal to 15? [A] 14 + 2 [B] 1 + 14 [C] 10 + 5 [D] 6 + 9 [E] 12 + 3

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Video Transcript

Which of these is not equal to 15? 14 plus two, one plus 14, 10 plus five, six plus nine, and 12 plus three?

Is 14 plus two equal to 15? To calculate 14 plus two, we could use a number line. Start at 14 and count forward two. One, two. 14 plus two is equal to 16. So, we know that this expression is not equal to 15. Is one and 14 equal to 15? Well, if we change the order of the calculation to 14 plus one, we can calculate one more than 14, which is 15. 10 plus five is equal to 15.

Is six plus nine equal to 15? To work this out, we could again change the order of the calculation to nine plus six. We start at nine on our number line and count forward six. One, two, three, four, five, six. Six plus nine or nine plus six is equal to 15.

Finally, is 12 plus three equal to 15? Well, we can start at 12 on the number line and count forward three. One, two, three. 12 plus three is equal to 15. The expression which is not equal to 15 is 14 plus two. 14 plus two equals 16. All of the other expressions equal 15.

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