Multiplying by 15 Made Easy

This video tutorial from Mumu Math and Science explains an easy method to multiply any number by 15. The method involves multiplying the number by 10, taking half of that result, and then adding the two results together. The video provides four examples to illustrate this technique: multiplying 9, 23, 36, and 420 by 15. Each example is broken down step-by-step to ensure understanding. The video concludes with a recap of the method and encourages viewers to subscribe for more math and science tutorials.

What is the first step in the method to multiply a number by 15?

• Multiply the number by 10

• Add 15 to the number

• Multiply the number by 5

• Divide the number by 2

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CCSS.5.NBT.A.2

After multiplying a number by 10, what is the next step in the method?

• Take half of the result

• Add 10 to the result

• Subtract 5 from the result

• Multiply the result by 2

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CCSS.4.NBT.B.5

Using the method, what is 9 times 15?

• 145

• 150

• 135

• 120

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CCSS.4.NBT.B.5

What is the result of 23 times 15 using the method described?

• 315

• 330

• 360

• 345

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CCSS.4.MD.C.5B

CCSS.HSG.CO.A.1

How do you calculate half of 360 in the method?

• 160

• 170

• 190

• 180

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CCSS.5.NBT.B.5

What is the final result of 36 times 15 using the method?

• 540

• 550

• 530

• 560

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CCSS.5.NBT.B.5

What is the result of 420 times 15 using the method?

• 630

• 650

• 620

• 640

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CCSS.5.NBT.B.5