How to tell the difference between a male and female cat?

If you look at the female cat's genital area,the space just under her tail,it will look like an upside down an exclamation mark (!) with the long slit of vaginal area  below the anus.  while the male cat has a narrow space between the anus and the penis, with the testicles in the middle... i hope u will understand!... :)

If your cat is female, you'll find her genital opening (vulva) immediately below her anus, and it will be in the shape of a vertical slit. If your cat is male, his genital opening (penis) will be a noticeable distance from his anus – about ½ inch in kittens and 1 inch in adults – and will be a rounded shape

Mg is used to measure mass