Maths Quiz - Tell me how it is done...please?

1. a,b,c,d are the first four digits.

The number entered equals 1000a+100b+10c+d

2. 80(1000a+100b+10c+d)

3. 80(1000a+100b+10c+d) + 1

4. 250×80(1000a+100b+10c+d) + 250 = 20,000(1000a+100b+10c+d) + 250

5&6. e,f,g,h are the last four digits.

20,000(1000a+100b+10c+d) + 250 + 2(1000e+100f+10g+h)

7. 20,000(1000a+100b+10c+d) + 2(1000e+100f+10g+h)

8. 10,000(1000a+100b+10c+d) + 1000e+100f+10g+h

This is the number represented by the digits abcdefgh.

Of course, it only works if your area has 8-digit telephone numbers.

Now I got it... sort of... it's the phone number except messed up a little.

I guess this is done like this: first they add four 0's (250 * 80 = 20 000). Then they make you add your phone number twice, this is so that when you divide the number by 2 later, the phone number won't be halved.

I'm not sure about the adding 1 and subtracting 250 yet.

I'm not exactly sure how the trick works. I think that you have step number one wrong. I always do it the first three digits, not including the area code. This way, you are entering your entire phone number, in your way the fourth number will be repeated and you will not get yur phone number as an anwer. I know I wasn't very helpful, sorry.

It was my phone mumber all but one number,

good one