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Year 7 · Maths · Calculating with numbers · Lesson 1

Adding and subtracting decimals

Add and subtract decimals using the column method, lining up decimal points, and solve money and measure problems.

Whiteboard video lesson: Adding and subtracting decimals

26-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Line up decimal points
  • Add decimals with carrying
  • Subtract decimals with exchanging
  • Subtract from whole numbers
  • Solve money and measurement problems

The method

  1. Line up the decimal points.
  2. Fill gaps with zeros.
  3. Work from the right; carry or exchange.
  4. Put the decimal point in the answer.

Key words: decimal, column method, carry, exchange, decimal point.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

Work out 2.4 + 3.5.

  1. Step 1: Line up the decimal points.
  2. Step 2: Add the columns

Answer: 5.9

Question 2

Work out 4.62 + 1.25.

  1. Step 1: Line up the decimal points.
  2. Step 2: Add the columns

Answer: 5.87

Question 3

Work out 7.8 + 4.6.

  1. Step 1: Line up the decimal points.
  2. Step 2: Add the columns

Answer: 12.4