Originally posted by: AnnihilatorX
It's nothing fancy. Anyone who can do algebra can
proof that
Let first three digits of your phone number be x
And last 4 digits of your phone number be y
So that your phone number is actually 10000*x + y
Say your number is 123 4567
123 * 10000 + 4567 = 1234567
Now the formula:
"Take first 3 digits multiply by 80, add 1 then times the result by 250, add last 4 digits 2 times, minus result by 250 and divide the result by 2" can be written as follows:
[(80x + 1)*250 +2y - 250] / 2
= [20000 x + 250 + 2y - 250] / 2
=(20000x + 2y) / 2
= 10000x + y
= your original phone number
These tricks can be formulated with any set of numbers easily if you spend a little time on formulating them.