Calculate the Percentage: Finding 7% of 90

Q: Why do I need to divide by 100 to convert a percentage?

The percent symbol (%) literally means 'per hundred' or 'out of 100'. So 7% means $ \frac{7}{100} $, which equals 0.07 as a decimal.

Q: Can I use the fraction method instead of decimals?

Yes! You can calculate $ \frac{7}{100} \times 90 $. This gives you $ \frac{630}{100} = 6.3 $, the same answer as the decimal method.

Q: How can I quickly check if 6.3 makes sense?

Use estimation: 7% is close to 10%, and 10% of 90 is 9. Since 6.3 is less than 9, it's reasonable for 7% of 90.

Q: Is there a shortcut for calculating percentages?

For mental math, you can think: 1% of 90 is 0.9, so 7% of 90 is 7 × 0.9 = 6.3. This uses the fact that 1% = $ \frac{1}{100} $.

Percentage Calculations with Decimal Conversion

Calculate 7% of 90:

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:03 Let's calculate seven percent of ninety.

00:06 First, convert seven percent into a fraction.

00:17 This fraction represents seven percent.

00:23 Now, multiply this fraction by ninety.

00:29 Try to factorize and simplify if you can.

00:39 And that's how we find the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Calculate 7% of 90:

Step-by-step solution

To solve this problem, we'll follow these steps:

Step 1: Convert the percentage to a decimal.
Step 2: Multiply the decimal by the whole number.

Now, let's work through each step:
Step 1: To convert the percentage 7% to a decimal, divide by 100. Thus, $7\% = \frac{7}{100} = 0.07$ .
Step 2: Multiply the decimal 0.07 by the whole number 90. Therefore, $0.07 \times 90 = 6.3$ .

Therefore, the solution to the problem is $6.3$ .

Final Answer

6.3

Key Points to Remember

Essential concepts to master this topic

Rule: Convert percentage to decimal by dividing by 100
Technique: Multiply decimal by whole number: 0.07 × 90 = 6.3
Check: Verify that 6.3 is 7% of 90 by calculating 6.3 ÷ 90 = 0.07 ✓

Common Mistakes

Avoid these frequent errors

Multiplying percentage directly without converting to decimal
Don't multiply 7 × 90 = 630! This treats 7% as the whole number 7, giving a result that's 100 times too large. Always convert the percentage to a decimal first by dividing by 100.

Practice Quiz

Test your knowledge with interactive questions

Calculate 30 over 100 as a percentage:

FAQ

Everything you need to know about this question

Why do I need to divide by 100 to convert a percentage?

The percent symbol (%) literally means 'per hundred' or 'out of 100'. So 7% means $\frac{7}{100}$ , which equals 0.07 as a decimal.

Can I use the fraction method instead of decimals?

Yes! You can calculate $\frac{7}{100} \times 90$ . This gives you $\frac{630}{100} = 6.3$ , the same answer as the decimal method.

What if I get a different decimal answer?

Double-check your conversion: 7% = 0.07 (not 0.7 or 0.007). Then verify your multiplication: 0.07 × 90 = 6.3. A common error is misplacing the decimal point.

How can I quickly check if 6.3 makes sense?

Use estimation: 7% is close to 10%, and 10% of 90 is 9. Since 6.3 is less than 9, it's reasonable for 7% of 90.

Is there a shortcut for calculating percentages?

For mental math, you can think: 1% of 90 is 0.9, so 7% of 90 is 7 × 0.9 = 6.3. This uses the fact that 1% = $\frac{1}{100}$ .

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