Work Text:
Dean's first day of algebra class surprised the crap out of him because apparently he'd been doing algebra for years.
He'd thought he'd just figured out how to cheat at real life math.
Once Sammy started full day kindergarten, Dad started leaving them alone overnight to go on hunts.
Within a year, Dad would be gone for weeks at a time, trusting Dean to take care of Sammy.
After the first time Dean went hungry so Sammy didn't have to, he started doing grocery store math in his head every time he saw or thought about food.
Compulsively.
After the first time they almost got evicted from a motel because the rent came due when Dad was gone, he became hyper-aware of the calendar.
Not long after, Dean was running calculations in his head so constantly that by the time Dad finished any sentence including the phrases "I'll be gone for" or "I'll be back in" Dean knew how much they'd need just to survive (doubling the length of time Dad said he'd be gone out of bitter experience) and could make a reasonable guess at how much he could actually get out of Dad.
If the second number always exceeded the first, he'd have almost preferred Dad to be away. It was just easier.
The first time Dean sucked off a pervert in an alley because Dad hadn't left enough even if he'd been back on time, Dean thought real hard about the math.
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