Hangman was a maths kid in school. English was never his strong suit and numbers came much more naturally to him. So much so, that he still demonstrates this talent in the navy.
Coyote noticed this when he was trying to pay the bill at the Hard Deck, and before Penny could say the amount owed, Hangman just blurted out the total.
"How'd you get that?"
Hangman shrugged, "I counted."
"The whole night?"
"No, just now. Didn't want you paying too much."
Coyote was even more shocked when Penny said he was right.
Phoenix, the secret keeper of literally everybody, also knew of his skill when Hangman calculated the speed of a plane in his head when he only knew the distance and time.
"speed is distance divided by time" was the only explanation she got but from then on she knew.
Hangman also was the only person to keep track of the score of their football beach game, and do so accurately. But he didn't tell anyone because his team lost.
Rooster doesn't put two and two together until he finds an old report card of Hangmans and finds the A* next to maths, and suddenly remembers every time Hangman has been absurdly good with numbers.
"YOU'RE A MATH KID!"
Hangman turned to look at him, "yeah? I didn't try to keep it a secret but it wasn't a big deal. I had bigger things to worry about."
"You also got a D in english... is that why you're called Hangman? You can't spell?"
"Bradley I swear to god-"
