i objectively agree with you but what specifically are you referring to about jkr not knowing how to do math akdjnakjsnd

warmhappycat:

So much.  

• She spat out years for people’s birthdays without doing the math, and now Bellatrix’s dad is only 13 years older than her.  
• Birthdays and death days are wild.  Wizards either live to be 150 or they die at 40.  
• Obviously Cursed Child is garbage, but if we were to accept it as canon, either Bellatrix was sooo old when Delphi was born or Andromeda was sooo young when Tonks was born.  
• In fact, everyone seems to have their kids stupid young, despite the fact that wizards have longer lifespans and therefore presumably have proportionally longer fertile years, which again makes me think she spat out birth years without really thinking it through.  
• Allegedly there are 1000 students at Hogwarts at any given time, but there were only about 40 kids in Harry’s year, which would be more like 280 total students (and even if the birth rate HALVED during the war, it’s still nowhere near 1000).  
• I have lost years of my life trying to figure out how Euphemia Potter could be fertile and healthy enough to have a baby and then die at an “advanced age” less than 20 years later.  
• I have offered similar numbers of years in return for understanding Fenrir Greyback’s age, but the Devil insists I’m still lowballing him.  (How old was he when he bit Remus?  To be so established in the werewolf community, he must have been an adult, right?  Maybe early 30s?  But that would make him in his 60s, minimum, during the second war.  He certainly wasn’t portrayed as that old in the movies, although I can’t concern myself too much with the sins of the movies.  How long do werewolves usually live?)
• Sirius specifically said that Snape used to hang out with Bellatrix at Hogwarts, but Bellatrix would have been loooong graduated by the time Snape started.  
• Dumbledore claimed to enjoy Bernie Bott’s Every Flavor Beans as a boy, but he was solidly an adult when they were invented.