# How much is 90 percent of twenty one

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We think you reached us looking for answers to questions like: What is 90 percent of twenty one? Or maybe: How much is 90 percent of twenty one

See the detailed solutions to these problems below.

## How to work out percentages explained step-by-step

Learn how to solve percentage problems through examples.

In all the following questions consider that:

• The percentage figure is represented by X%
• The whole amount is represented by W
• The portion amount or part is represented by P

### Solution for 'What is 90% of twenty one?'

#### Solution Steps

The following question is of the type "How much X percent of W", where W is the whole amount and X is the percentage figure or rate".

Let's say that you need to find 90 percent of 21. What are the steps?

Step 1: first determine the value of the whole amount. We assume that the whole amount is 21.

Step 2: determine the percentage, which is 90.

Step 3: Convert the percentage 90% to its decimal form by dividing 90 into 100 to get the decimal number 0.9:

90100 = 0.9

Notice that dividing into 100 is the same as moving the decimal point two places to the left.

90.0 → 9.00 → 0.90

Step 4: Finally, find the portion by multiplying the decimal form, found in the previous step, by the whole amount:

0.9 x 21 = 18.9 (answer).

The steps above are expressed by the formula:

P = W × X%100

This formula says that:

"To find the portion or the part from the whole amount, multiply the whole by the percentage, then divide the result by 100".

The symbol % means the percentage expressed in a fraction or multiple of one hundred.

Replacing these values in the formula, we get:

P = 21 × 90100 = 21 × 0.9 = 18.9 (answer)

Therefore, the answer is 18.9 is 90 percent of 21.

### Solution for '90 is what percent of twenty one?'

The following question is of the type "P is what percent of W,” where W is the whole amount and P is the portion amount".

The following problem is of the type "calculating the percentage from a whole knowing the part".

#### Solution Steps

As in the previous example, here are the step-by-step solution:

Step 1: first determine the value of the whole amount. We assume that it is 21.

(notice that this corresponds to 100%).

Step 2: Remember that we are looking for the percentage 'percentage'.

To solve this question, use the following formula:

X% = 100 × PW

This formula says that:

"To find the percentage from the whole, knowing the part, divide the part by the whole then multiply the result by 100".

This formula is the same as the previous one shown in a different way in order to have percent (%) at left.

Step 3: replacing the values into the formula, we get:

X% = 100 × 9021

X% = 900021

So, the answer is 90 is 428.57 percent of 21

### Solution for '21 is 90 percent of what?'

The following problem is of the type "calculating the whole knowing the part and the percentage".

### Solution Steps:

Step 1: first determine the value of the part. We assume that the part is 21.

Step 2: identify the percent, which is 90.

Step 3: use the formula below:

W = 100 × PX%

This formula says that:

"To find the whole, divide the part by the percentage then multiply the result by 100".

This formula is the same as the above rearranged to show the whole at left.

Step 4: plug the values into the formula to get:

W = 100 × 2190

W = 100 × 0.23333333333333