Knowing a percentage or a fraction of a number can be useful in many situations in everyday life, for example:
  1. When buying discounted products. Knowing the discount percentage allows you to calculate the final cost of the product.
  2. When calculating the interest rate on the loan. Knowing the percentage allows you to calculate the total amount that will need to be paid for the loan.
  3. When calculating taxes. Knowing the tax percentage allows you to calculate the amount of tax that will need to be paid.
  4. When calculating the tip amount. Knowing the tip percentage allows you to calculate the amount you need to leave to the waiter.
  5. When calculating the percentage of profit. Knowing the percentage of profit allows you to evaluate the effectiveness of the business.
  6. When calculating the percentage of population or economic growth. Knowing the percentage of growth allows you to estimate the pace of development of a country or region.

What is 21 percent of 400?

 

Method 1: Multiplying a number by a percentage value

This method is based on the fact that a percentage is a fraction of 100.

That is, if we need to calculate 21% of the number 400, we can represent it as 21/100, which is equal to 0.21.

Then we multiply 400 by 0.21 to get the answer.

Formula: percentage of number = number x (percentage / 100)

Example: Calculate 21% of 400.

Solution: 400 x (21 / 100) = 84

Answer: 21% of 400 is equal to 84.

Method 2: Dividing a number by 100 and multiplying by a percentage

This method is also based on the fact that a percentage is a fraction of 100.

However, instead of multiplying the number by a percentage, we divide the number by 100 and then multiply the result by a percentage.

Formula: percentage of number = (number / 100) x percentage

Example: Calculate 21% of 400.

Solution: (400 / 100) x 21 = 84

Answer: 21% of 400 is equal to 84.

Method 3: Simple fraction

This method is based on the fact that a percentage is a fraction of 100.

We can represent a percentage as a simple fraction, where the numerator is a percentage and the denominator is 100.

Then we multiply this by a number to get the answer.

Formula: percentage of number = (percentage / 100) x number

Example: Calculate 21% of 400.

Solution: (21 / 100) x 400 = 84

Answer: 21% of 400 is equal to 84.

All three methods give the same result. Choose the one that is more convenient for you.

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