To add decimals, align the numbers by the decimal point, add zeros if necessary to make the numbers the same length, and then add as you would with whole numbers, placing the decimal point in the sum directly below the aligned decimal points.

To subtract decimals, align the numbers by the decimal point, add zeros if necessary to make the numbers the same length, and then subtract as you would with whole numbers, placing the decimal point in the difference directly below the aligned decimal points.

The place value of a decimal number is determined by the position of each digit relative to the decimal point. To the left of the decimal, the values are whole numbers (units, tens, hundreds, etc.), and to the right, the values are fractions (tenths, hundredths, thousandths, etc.).

0.5 in fraction form is 1/2.

To convert a decimal to a percentage, multiply the decimal by 100 and add a percent sign. For example, 0.75 becomes 75%.

The sum of 0.1 and 0.2 is 0.3.

The difference between 3.5 and 1.2 is 2.3.