Actually, as the OP said she "got her period" i.e.; started it, the odds would be much lower. If she was regular as clockwork at 28 days per cycle, that would be 13 times a year, which means there would be a 3.6% chance the first day of a period would coincide with her birthday, meaning it happened roughly once every 28 years. Bloody statistics...

If you're into maths/science, a calculator is an extremely useful present. As for the period part, well, you either will get used to it, or you should be by now. Though if you're unlucky enough to get seriously ill each month, then I can understand why you're complaining about that.

put it to good use and do some bloody math ;-)

Girl, graphing calculators are expensive.

At least you're not pregnant.

i would personally love to get a calculator for my birthday :P those things are awesome, but most are pretty expensive :(

graphing calculators are expensive so be happy. ohh and periods arnt that bad just take midol?

In other words, you received an expensive gift and found out you don't have to worry about being pregnant. Sounds like a good birthday to me.....

HAPPY BIRTHDAY!

Pop a frickin' midol and stop bitching. "Today, for my birthday, I got an expensive and very useful present, and also went through something every single female on the planet goes through. Boohoo, boohoo."

So OP, which are you complaining about? The graphing calculator or your period?

its the thought that counts!:D be happy you got something!