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.