Think of a Number

Instructions Try your best to answer the questions above. Type your answers into the boxes provided leaving no spaces. As you work through the exercise regularly click the "check" button. If you have any wrong answers, do your best to do corrections but if there is anything you don't understand, please ask your teacher for help. When you have got all of the questions correct you may want to print out this page and paste it into your exercise book. If you keep your work in an ePortfolio you could take a screen shot of your answers and paste that into your Maths file.

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Mathematicians are not the people who find Maths easy; they are the people who enjoy how mystifying, puzzling and hard it is. Are you a mathematician? Comment recorded on the 10 April 'Starter of the Day' page by Mike Sendrove, Salt Grammar School, UK.: "A really useful set of resources - thanks. Is the collection available on CD? Are solutions available?" Comment recorded on the 26 March 'Starter of the Day' page by Julie Reakes, The English College, Dubai: "It's great to have a starter that's timed and focuses the attention of everyone fully. I told them in advance I would do 10 then record their percentages."		Each month a newsletter is published containing details of the new additions to the Transum website and a new puzzle of the month. The newsletter is then duplicated as a podcast which is available on the major delivery networks. You can listen to the podcast while you are commuting, exercising or relaxing. Transum breaking news is available on Twitter @Transum and if that's not enough there is also a Transum Facebook page.
Featured Activity Connect 4 Factors A mathematical version of the popular Connect 4 game based on getting four numbers with a common factor in a line. Fun for one, two or a whole class of pupils.	Answers There are answers to this exercise but they are available in this space to teachers, tutors and parents who have logged in to their Transum subscription on this computer. A Transum subscription unlocks the answers to the online exercises, quizzes and puzzles. It also provides the teacher with access to quality external links on each of the Transum Topic pages and the facility to add to the collection themselves. Subscribers can manage class lists, lesson plans and assessment data in the Class Admin application and have access to reports of the Transum Trophies earned by class members. If you would like to enjoy ad-free access to the thousands of Transum resources, receive our monthly newsletter, unlock the printable worksheets and see our Maths Lesson Finishers then sign up for a subscription now: Subscribe
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Example

Daniel says 'If I double my number and add 6 the answer is 30'

Method 1 - Work backwards

Start at the end of the sentence with the answer 30 and undo all of the operations Daniel performed on his number in reverse order.

30 minus 6 then divide by two

The number Daniel was thinking about was 12

Method 2 - Form and solve an equation

Let the number that Daniel is first thinking of be n.

2n + 6 = 30

Subtract 6 from both sides

2n = 24

Divide both sides by 2

n = 12

The number Daniel was thinking about was 12

Don't wait until you have finished the exercise before you click on the 'Check' button. Click it often as you work through the questions to see if you are answering them correctly. You can double-click the 'Check' button to make it float at the bottom of your screen.

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\( \times 2\) \(+3\) \(7\) Brooklyn says: 'I think of a number. I double my number and add 3 the answer is 7' What number was Brooklyn first thinking of?	Working:
Vanessa says: 'I am also thinking of a number. If I multiply my number by 2 and add 6 the answer is 46' What number was Vanessa first thinking of?	Working:
Amanda says: 'I think of a number. I multiply my number by 3 and add 5 the answer is 41' What number was Amanda first thinking of?	Working:
Ariana says: 'Can you guess what number I am thinking of if when I multiply it by 2 and add 6 the answer is 18?' What number was Ariana first thinking of?	Working:
Rebecca says: 'If I divide my number by 5 and add 6 the answer is 15' What number was Rebecca first thinking of?	Working:
Caroline says: 'If I multiply my number by 4 then add 2 then add 2 then add 6 the answer is 34' What number was Caroline first thinking of?	Working:
Amelia says: 'I am thinking of my favourite number. If I add 8 to my number then divide the result by 2, the answer is 9' What number was Amelia first thinking of?	Working:
Mariah says: 'My plan was to add 3 to my number then multiply the result by 4. Then I multiplied the result by 3 and finally subtracted 2. The answer is 118' What number was Mariah first thinking of?	Working:
Jordan says: 'I decided to add 3 to my number then multiply the result by 3, After that I subtracted 5 then doubled the result. The answer is 104' What number was Jordan first thinking of?	Working:
Jocelyn says: 'If I multiply my number by 2 and subtract 3 then multiply the result by 4, the answer is 3 less than 127' What number was Jocelyn first thinking of?	Working:

Think of a Number

Ten students think of a number then perform various operations on that number. You have to find what the original numbers were.

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Instructions

More Activities:

Featured Activity

Connect 4 Factors

Answers

Go Maths

Maths Map

Teachers

Description of Levels

Curriculum Reference

Example

Method 1 - Work backwards

Method 2 - Form and solve an equation