Interesting and easy math game

[scaeagles]

You'll need a calculator. Well, you probably don't NEED one, but you'll want one.

Take the first three digits of your telephone number (not the area code).

Multiply by 80.

Add 1.

Multiply by 250.

Add the last 4 digits of your telephone number.

Add the last 4 digits of your telephone number again.

Subtract 250.

Divide by 2.

What is the result? I found this to be quite tricky.

[wendybeth]

Is it supposed to be your phone number? I ran it twice, and it gave me the same number, which is a few digits off from my phone number.

[scaeagles]

It is. I am curious as to why it does not work with yours, as I have tried it with probably 15 different numbers and it works every time. Hmmm....

[lizziebith]

Yeah! I got my phone number. Here's another weird game (you must have flash to play).

[scaeagles]

I was able to figure out the secret to that one after just 2 tries. I still can't figure out the math behind the one I posted and why it works every time. Except for WB. I'm think the problem isn't with the game, though, WB.

[Ghoulish Delight]

Originally Posted by scaeagles

I was able to figure out the secret to that one after just 2 tries. I still can't figure out the math behind the one I posted and why it works every time. Except for WB. I'm think the problem isn't with the game, though, WB.

Well, if X=the first 3 digits of your phone number and Y=the last 4, then your phone number can be represented as 10000X+Y

So, the operations you perform look like this:

(80X+1)*250+2Y-250
___________________
2

Simplifying the numerator, you get 20000X+250+2Y-250.

The +250 and -250 cancel out, leaving you with 20000X+2Y. Divide that by 2 and you get 10000X+Y, which of course is your phone number.

[wendybeth]

Originally Posted by Ghoulish Delight

Well, if X=the first 3 digits of your phone number and Y=the last 4, then your phone number can be represented as 10000X+Y

So, the operations you perform look like this:

(80X+1)*250+2Y-250
___________________
2

Simplifying the numerator, you get 20000X+250+2Y-250.

The +250 and -250 cancel out, leaving you with 20000X+2Y. Divide that by 2 and you get 10000X+Y, which of course is your phone number.

My brain hurts just looking at that.

[wendybeth]

Originally Posted by scaeagles

It is. I am curious as to why it does not work with yours, as I have tried it with probably 15 different numbers and it works every time. Hmmm....

Operator error- I drank another cup of coffee and ran it again. Worked fine.

[scaeagles]

So my presumption was correct, then.

[wendybeth]

It's no secret that I am mathmatically challenged, Scaeagles. I'm rather smug about it, actually. I think that when you find something you're good at, you should be proud of that, and I'm real good at being bad at math.