Calculating Percentages and Fractions

The video tutorial guides viewers through calculating various percentages mentally. It begins with an introduction to mental math and explains how to calculate percentages like 1%, 10%, 20%, 25%, 50%, and 400% using simple division and multiplication. Each percentage is broken down into a fraction, making it easier to compute without writing down the calculations.

Why is it useful to calculate percentages mentally?

• It helps in understanding complex algebra.

• It is a requirement for all math exams.

• It is more accurate than using a calculator.

• It saves time in everyday calculations.

What is 1% of 900?

• 0.9

• 900

• 9

• 90

How can 10% of a number be calculated easily?

• Divide the number by 100.

• Multiply the number by 100.

• Divide the number by 10.

• Multiply the number by 10.

What is 10% of 630?

• 6.3

• 0.63

• 630

• 63

What fraction is equivalent to 20%?

• 1/10

• 1/5

• 1/2

• 1/4

What is 20% of 45?

• 9

• 4.5

• 18

• 2.25

What fraction is equivalent to 25%?

• 1/5

• 1/3

• 1/2

• 1/4

What is 25% of 28?

• 14

• 5.6

• 2.8

• 7

What is 50% of 128?

• 16

• 64

• 32

• 128

How is 400% of a number calculated?

• Add 400 to the number.

• Subtract 400 from the number.

• Multiply the number by 4.

• Divide the number by 4.