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      Use known facts from the 10 times table to solve problems involving the 9 times table

      Lesson details

      Learning outcome

      I can use known facts from the 10 times table to solve problems involving the 9 times table.

      Key learning points

      1. If 9 is equal to 10 subtract 1 then 9 groups of 15 is equal to 10 groups of 15 subtract 1 group of 15
      2. Facts from the 10 times table can be used to solve problems involving the 9 times table.
      3. 10 times a number and 9 times a number are adjacent multiples.

      Keywords

      • Array - An array is the layout of items (such as objects, numbers etc.) arranged in rows and / or columns.

      Common misconception

      Lack of fluency in 9 times tables and not understanding the problems.

      To clearly model highlighting key words of worded problems to understand the problem and the operation required for the calculation. Continue to use language stems such as 'If I know...' 'Then I know...,' to support mathematical thinking.

      Teacher tip

      By this lesson, pupils should be fluent in the 9s and 10s. Continue to use language which reflects the relational pattern between 10s and 9s e.g. 'If I know that 9 × 10 = 90 then I know that 9 × 11 is 99 because you add one more group of 9'

      Licence

      This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      Identify the multiples of 10

      25
      Correct answer: 40
      99
      Correct answer: 100
      Correct answer: 140

      Q2.
      Books cost £10 and Jun buys four. How much does he spend? £

      Correct Answer: 40, 40.00

      Q3.
      Which multiple of 9 is missing from this sequence? 18, 27, , 45

      Correct Answer: 36

      Q4.
      What is 11 × 9 =

      Correct Answer: 99

      Q5.
      What is 15 × 10 =

      Correct Answer: 150

      Q6.
      What is 37 × 10 =

      Correct Answer: 370

      6 Questions

      Q1.
      What fact can I use to efficiently calculate 7 × 9?

      7 × 7
      Correct answer: 7 × 10
      7 + 9
      7 × 9 + 1

      Q2.
      Complete: 7 × 10 − = 7 × 9

      Correct Answer: 7

      Q3.
      Complete: 10 × 12 − = 12 × 9

      Correct Answer: 12

      Q4.
      What do I need to subtract from 45 × 10 to find 45 × 9?

      1
      9
      10
      Correct answer: 45

      Q5.
      Use 21 × 10 = 210 to calculate 21 × 9 =

      Correct Answer: 189

      Q6.
      Use 34 × 10 = 340 to calculate 34 × 9 =

      Correct Answer: 306

      To help you plan your 4 maths lesson on: Use known facts from the 10 times table to solve problems involving the 9 times table, download all teaching resources for free and adapt to suit your pupils' needs...