Some birthday maths thing...

[mendhak]

Take the date you were born on.
Multiply it by 4.
Add 13.
Multiply by 25.
Subtract 200.
Add the month you were born.
Multiply by 2.
Subtract 40.
Multiply by 50.
Add the last two digits of the year you were born.
Subtract 10500.

Notice something familiar about the result?

Any thoughts on how this was formulated?

[twanvl]

50(2(25(4d+13)-200+m)-40)-10500+y
=
50*2*25*4*d + 50*2*m + y + 50*2*25*13 - 50*2*200 - 50*40 - 10500
=
10000d + 100m + y + 32500 - 20000 - 2000 - 10500
=
10000d + 100m + y

[mendhak]

Oh... never mind then.

[MrPolite]

Originally posted by mendhak
Oh... never mind then.

it's the square root of your brain!

[Acidic]

let:
Y = last to digits of year you were born
M = Month you were born
D = Date you were born

then you get:
50(2((25(4D+13)-200)+M)-40) +Y - 10500
50(2((100D+325-200)+M)-40)+Y-10500
50(2(100D+125+M)-40)+Y-10500
50(200D+250+2M-40)+Y-10500
10000D+10500+100M+Y-10500
10000D+100M+Y

There you go, from there it is obvious.