Decimals are another way to represent parts of a whole, using the base-ten system. The decimal point separates the whole number part from the fractional part. The first digit after the decimal is in the tenths place, the second in the hundredths place, and so on.

To add or subtract decimals, line up the decimal points and add zeros as placeholders if needed. Then add or subtract as you would with whole numbers. To multiply decimals, multiply as if they were whole numbers, then count the total decimal places in both factors and place the decimal point in the product.

Decimals and fractions are closely related: 0.5 = 1/2, 0.25 = 1/4, 0.75 = 3/4. To convert a fraction to a decimal, divide the numerator by the denominator.