Year 8: Add and subtract decimal numbers

This cheat sheet will help you add and subtract decimal numbers.

Key concepts

• Decimal numbers: Numbers with a point (decimal point) separating whole numbers from parts of a whole.
• Place value: Understand the value of each digit in a decimal number (e.g., tenths, hundredths, thousandths).

Adding decimal numbers

1. Step 1: Line up the decimal points. This is crucial!
2. Step 2: Add the digits in each column, just like with whole numbers.
3. Step 3: Bring the decimal point straight down through the answer.

Example:$2.5+3.75=6.25$

Subtracting decimal numbers

1. Step 1: Line up the decimal points.
2. Step 2: Subtract the digits in each column.
3. Step 3: Bring the decimal point straight down through the answer.

Example:$8.3-2.75=5.55$

Tips

• Always line up the decimal points.
• Start by adding zeros as placeholders if needed to keep the numbers aligned.