THOAN

Boy

Sebastian thinks of a number. "If I double my number and add 5 the answer is 43"

Boy

Seth thinks of a number. "If I multiply my number by 5 and add 2 the answer is 42"

Girl

Sofia thinks of a number. "If I add 5 to my number then divide the result by 2, the answer is 12.5"

Girl

Sophia thinks of a number. "If I multiply my number by 3 and subtract 2 then multiply the result by 6, the answer is 2 less than 80"

What numbers are they thinking about?

Think Of A Number

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Topics: Starter | Algebra | Puzzles

  • C Fleming, Lancashire
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  • Unfortunately the faces on these starters are an excuse to be distracted for some of my pupils.
  • Yr6, CASTERTON PRIMARY SCHOOL
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  • It was quite a challenge but we achieved it!
  • Transum,
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  • While it is certainly possible to solve these problems by trial and improvement, older children could use the 'working backwards' method using inverse operations. Secondary students may decide to use algebra to produce a linear equation to be solved.
    Each time you refresh the page a new set of problems appear.
  • Year 7 St Michaels, St Michaels
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  • We found it hard but did it. We are amazing!
  • Noah, Charnwood Primary Lichfield, Year 6
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  • Not too tricky but you needed to read things carefully or it could catch you out. A good maths starter.
  • Transum,
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  • Here's a different type of THOAN mystery. Think of a three digit number that has all three digits the same. Divide the number by the sum of the digits. I know what your answer is! Is it 37?
  • Mrs Royde, Manchester
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  • The weakest girl in Year 9 bottom managed to work out one of these, much to my surprise. I asked her how she did it, she said 'I worked it out backwards'. I said, 'but you told me you can't do algebra!' She said 'this isn't algebra.' I told her it is, and then showed her how to write it using an x and how to figure it out. She was so chuffed that she had done it that she concentrated and worked brilliantly for the rest of the lesson.

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This starter has scored a mean of 3.3 out of 5 based on 559 votes.


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Answers:

Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.



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Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.

Transum.org/go/?Start=November1

Here is the URL which will take them to a related student activity.

Transum.org/go/?to=THOAN

Student Activity

 


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