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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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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\( \times 2\) \(+6\) \(20\) Caroline says: 'I think of a number. I double my number and add 6 the answer is 20' What number was Caroline first thinking of?	Working:
Amelia says: 'I am also thinking of a number. If I multiply my number by 2 and add 6 the answer is 24' What number was Amelia first thinking of?	Working:
Mariah says: 'I think of a number. I multiply my number by 3 and add 6 the answer is 69' What number was Mariah first thinking of?	Working:
Jordan says: 'Can you guess what number I am thinking of if when I multiply it by 5 and add 5 the answer is 30?' What number was Jordan first thinking of?	Working:
Jocelyn says: 'If I divide my number by 5 and add 6 the answer is 11' What number was Jocelyn first thinking of?	Working:
Arianna says: 'If I multiply my number by 4 then add 4 then add 5 then add 2 the answer is 91' What number was Arianna first thinking of?	Working:
Isabel says: 'I am thinking of my favourite number. If I add 4 to my number then divide the result by 2, the answer is 4' What number was Isabel first thinking of?	Working:
Marissa says: 'My plan was to add 3 to my number then multiply the result by 3. Then I multiplied the result by 4 and finally subtracted 2. The answer is 202' What number was Marissa first thinking of?	Working:
Autumn says: 'I decided to add 5 to my number then multiply the result by 3, After that I subtracted 5 then doubled the result. The answer is 86' What number was Autumn first thinking of?	Working:
Melanie says: 'If I multiply my number by 4 and subtract 2 then multiply the result by 2, the answer is 4 less than 160' What number was Melanie 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

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Featured Activity

Without Lifting

Answers

Go Maths

Maths Map

Teachers

Description of Levels

Curriculum Reference

Example

Method 1 - Work backwards

Method 2 - Form and solve an equation