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      Add multiples of 10 to 2-digit numbers.

      Lesson details

      Learning outcome

      I can use number facts to add multiples of 10 to two-digit numbers.

      Key learning points

      1. When adding multiples of ten to a two-digit number, the tens digit changes but the ones digit stays the same.
      2. Number facts can be used to help add and subtract multiples of ten to and from a two-digit number.

      Keywords

      • Multiples of ten - The numbers that are said when we count on in tens from zero. Multiples of ten always have a ones digit of zero.

      • Recombine - To add the parts of a number gained through partitioning the whole to reach the whole amount again.

      Common misconception

      Children may automatically count on in tens to add a multiple of ten.

      Discuss efficiency and compare different methods. Use practical equipment to draw attention to the relationship between adding multiples of ten in two-digit numbers and the known facts they already possess.

      Teacher tip

      When writing calculations, ensure that, if written as one continuous equation, the equals sign is used correctly and only used where the quantities on each side of the sign are equal, e.g. 37 + 40 = 30 + 40 + 7 = 70 + 7 = 77

      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.
      Match to complete the equations.

      Correct Answer:10 + 55 =,65

      65

      Correct Answer:39 + 10 =,49

      49

      Correct Answer:10 + 43 =,53

      53

      Correct Answer:89 + 10 =,99

      99

      Q2.
      Match to complete the equations.

      Correct Answer:29 − 10 =,19

      19

      Correct Answer:37 − 10 =,27

      27

      Correct Answer:55 − 10 =,45

      45

      Correct Answer:61 − 10 =,51

      51

      Q3.
      10 + 64 =

      Correct Answer: 74

      Q4.
      72 − 10 =

      Correct Answer: 62

      Q5.
      Match two numbers that have a difference of 10

      Correct Answer:23,33

      33

      Correct Answer:57,47

      47

      Correct Answer:46,56

      56

      Correct Answer:74,64

      64

      Q6.
      45 and ___ have a difference of 10

      44
      Correct answer: 55
      Correct answer: 35
      54

      6 Questions

      Q1.
      Look at the number line. What equation is it showing?

      An image in a quiz
      35 + 10 =
      35 + 20 =
      Correct answer: 35 + 30 =

      Q2.
      16 + 50 = ? How many tens are being added to 16 in this equation? tens

      Correct Answer: 5

      Q3.
      Which of the images represent this equation? 36 + 40 =

      Correct Answer: An image in a quiz
      An image in a quiz
      An image in a quiz
      An image in a quiz

      Q4.
      Match the known facts that will help to add multiples of 10

      Correct Answer:3 + 4 = 7,3 tens + 4 tens = 7 tens

      3 tens + 4 tens = 7 tens

      Correct Answer:2 + 6 = 8,20 + 60 = 80

      20 + 60 = 80

      Correct Answer:5 + 4 = 9,50 + 40 = 90

      50 + 40 = 90

      Q5.
      What could we do to help solve this equation? 32 + 40 =

      An image in a quiz
      Correct answer: Add 3 tens and 4 tens
      Add 3 tens and 2 tens
      Add 2 tens and 4 tens

      Q6.
      27 + 50 =

      Correct Answer: 77

      To help you plan your 2 maths lesson on: Add multiples of 10 to 2-digit numbers., download all teaching resources for free and adapt to suit your pupils' needs...