Finding a percentage of a whole number without a calculator: Basic

We can find the percentages of whole numbers without a calculator in some cases where standard percentages are involved. Some standard percentages are like 1%, 10%, 25%, 50%, 100%.

Rules to find the percentage of a whole number without a calculator

• To find 1% of any whole number, we shift the decimal two places to the left in the whole number.

• To find 10% of any whole number, we shift the decimal one place to the left in the whole number.

• To find 25% of any whole number, we divide the whole number by 4.

• To find 50% of any whole number, we divide the whole number by 2.

• To find 100% of any whole number, we keep the whole number as it is.

What is 10% of 180?

Solution

Step 1:

To find 10% of any whole number, we shift the decimal one place to the left in the whole number.

Step 2:

So, 10% of 180 is found by shifting the decimal point one place to left 180 = 180.0

So, 10% of 180 = 18.00 = 18

What is 25% of 70?

Solution

Step 1:

To find 25% of any whole number, we divide the whole number by 4.

Step 2:

25% of 70 is found by divide the whole number by 4.

So, 25% of 70 = $\frac{70}{4} = 17.50$

What is 100% of 127?

Solution

Step 1:

To find 100% of any whole number, we keep the whole number as it is.

Step 2:

So, 100% of 127 is found by keeping the whole number 127 as it is

So, 100% of 127 = 127