How is a percentage calculated mentally using estimation?

How is a percentage calculated mentally using estimation?

• A. By moving the decimal point one place to the left for 1%
• B. By adding the percentage to the original number
• C. By multiplying the number by the percentage
• D. By finding 10% and adjusting

Answer: (D)

Finding a percentage using estimation is effectively done through the method of determining 10% and then adjusting from there. When you find 10% of a number, you can easily scale it up to find other percentages. For instance, if you need to calculate 20%, you would simply double the 10% value. This method is particularly useful for mental calculations because it simplifies the process and allows you to make quick approximations. For example, to find 15% of a number, you could first calculate 10% and then add half of that value (which corresponds to 5%). This approach leverages the simplicity of calculating 10%—which is straightforward, as it often involves moving the decimal point one place to the left. Using this technique allows for flexibility in estimating various percentages and can often make calculations much quicker and more manageable in everyday situations.

Finding a percentage using estimation is effectively done through the method of determining 10% and then adjusting from there. When you find 10% of a number, you can easily scale it up to find other percentages. For instance, if you need to calculate 20%, you would simply double the 10% value.

This method is particularly useful for mental calculations because it simplifies the process and allows you to make quick approximations. For example, to find 15% of a number, you could first calculate 10% and then add half of that value (which corresponds to 5%). This approach leverages the simplicity of calculating 10%—which is straightforward, as it often involves moving the decimal point one place to the left.

Using this technique allows for flexibility in estimating various percentages and can often make calculations much quicker and more manageable in everyday situations.