Calculating Percentages and Mental Math

This video tutorial teaches how to calculate percentages mentally without a calculator. It covers several examples, including finding 15% of 200, 25% of 300, 40% of 500, 24% of 80, 33% of 120, and 18% of 39. Each example demonstrates breaking down percentages into smaller, manageable parts, confirming results with a calculator, and applying these skills to real-life scenarios like calculating tips.

What is the first step in calculating 15% of 200 mentally?

• Find 5% of 200

• Find 10% of 200

• Find 20% of 200

• Find 25% of 200

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CCSS.6.RP.A.3C

How do you calculate 5% of a number if you know 10% of it?

• Multiply 10% by 2

• Add 10% to itself

• Divide 10% by 2

• Subtract 10% from itself

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CCSS.6.RP.A.3C

What is the result of adding 10% and 5% of 200?

• 15

• 25

• 35

• 30

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CCSS.6.RP.A.3C

What is the value of 25% of 300?

• 75

• 100

• 90

• 60

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CCSS.6.RP.A.3C

How do you find 40% of 500 using mental math?

• Multiply 10% by 5

• Multiply 10% by 4

• Multiply 10% by 6

• Multiply 10% by 3

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CCSS.4.NBT.B.5

What is the result of multiplying 50 by 4?

• 250

• 150

• 300

• 200

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CCSS.6.RP.A.3C

What is the first step in calculating 24% of 80?

• Find 25% of 80

• Find 20% of 80

• Find 5% of 80

• Find 10% of 80

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CCSS.6.RP.A.3C

How do you calculate 4% of 80?

• Multiply 10% by 4

• Multiply 2% by 4

• Multiply 5% by 4

• Multiply 1% by 4

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CCSS.6.RP.A.3C

What is the value of 33% of 120?

• 36.6

• 39.6

• 45.6

• 42.6

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CCSS.6.RP.A.3C

How do you calculate 18% of 39?

• Add 10%, 4%, and 4% of 39

• Add 10%, 5%, and 3% of 39

• Add 10%, 7%, and 1% of 39

• Add 10%, 6%, and 2% of 39

Tags

CCSS.6.RP.A.3C