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Year 6 · Maths · Algebra and sequences · Lesson 2

Using simple formulae

Substitute values into simple formulae, including real-life formulae for costs and times, and write formulae from words and patterns.

Whiteboard video lesson: Using simple formulae

20-minute video lesson

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

Watch free for a month

What your child will learn

  • Understand algebraic notation like 3n
  • Substitute into formulae
  • Use real-life formulae
  • Write simple formulae

The method

  1. Write the formula.
  2. Swap each letter for its number.
  3. Put back the × signs.
  4. Calculate with BIDMAS.

Key words: formula, substitute, variable, expression, BIDMAS.

Worked examples

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

Question 1

Use the formula y = 2n + 1 to find y when n = 4.

  1. Step 1: y = 2n + 1
  2. Step 2: n = 4
  3. Step 3: y = 2 × 4 + 1 = 9

Answer: y = 9

Question 2

Use the formula y = 5n − 3 to find y when n = 6.

  1. Step 1: y = 5n − 3
  2. Step 2: n = 6
  3. Step 3: y = 5 × 6 − 3 = 27

Answer: y = 27

Question 3

Use the formula a = b + 12 to find a when b = 9.

  1. Step 1: a = b + 12
  2. Step 2: b = 9
  3. Step 3: a = 9 + 12 = 21

Answer: a = 21