1. ## Phone number witchcraft

Not really a puzzle but still good fun:

This will only work if you have a seven digit phone no. If you are in the UK and your number is like 0208 123 4567 just make it 123 4567.

Now here is the witchcraft:

Grab a calculator.
Type in the first three numbers of your seven digit telephone number.
Multiply by 80
Multiply by 250
Subtract 250
Divide by 2

What is the final number?

2. ## Re: Phone number witchcraft

Type in the first three numbers of your seven digit telephone number.
Multiply by 80 [80x]
Multiply by 250 [20,000x +250]
Add the last four digits of your number [20,000x + 250 +y]
Add them again [20,000x + 250 +2y]
Subtract 250[20,000x +2y]
Divide by 2 [10,000x +y]

10,000x moves the number (x) 4 places to the left (adds 4 zeroes) and then you add the last 4 digit number (y)

Steve

3. ## Re: Phone number witchcraft

Thanks for diagnosing it Steve.

I have a penchant for these types of number games, I don't know if you saw some of my own in scuttlebutt at the end of last year (sadly the posts have expired now). This one is not my own as I saw it last night on a web page and thought I would share it.

When I do these or create new ones I visualise them as two seperate entities( like you have by calling them x and y) and then put the calculations in two columns in a spreadsheet and then manipulate the numbers in steps. In my opinion this one was not very well "disguised" as the factors of 80 and 250 gave a very big clue. Still fun though.

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