This post will show you how you can turn a little bit of maths in to a magic trick that you can try with your friends or family.

**Instructions**

- Let your friends choose a number in their head between 1 and 10 (lower numbers for simplicity)
- Ask them to double it
- Ask them to add 4
- Tell them to Half it
- Ask them to subtract the original number
- Ask them if the answer is 2

The answer to this question will always be 2 regardless of the number your friends chose.

**Solution**

If we change the above into an algebra equation, we can see the maths behind how this trick works.

Let x be the unknown number that your friend has selected.

We will now apply all of the steps above to x:

- x
- 2x
- 2x + 4
- (2x + 4) / 2 = x + 2
- X + 2 – x
- 2

As you can see the main trick to this is the unknown number that your friend has selected, by asking them to minus the original number from the equation we are effectively removing the unknown from the equation.

See if you can create your own magic steps and lets us know in the comments below!

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Thank you for sharing your skills!

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Thanks

I love math and magic like Martin Gardner.

Nice blog topics! I’ll be back.

We all need simplification tips like you offer

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Reblogged this on Truth Troubles.

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Seems interesting. Can’t wait to try it.

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Thank-you.

I want to work at this…

Younger – primary school, I enjoyed maths – algebra my favourite…

Secondary school, aged 12, failure set in, badly….

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Thanks for explaining it! Never really thought about why

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I could have used this about 3 semesters past! Very helpful.

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Hi, can I share this game on my blog? I have a daily post called Quiz time and everyday I put a question (mainly mathematical). I find this one very nice 🙂

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Sure you can 🙂

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