Concept: In The Burning Maze, I think it would have been cool if one of the crossword puzzles in the labyrinth had been a mathematical equation.
Specifically, a mathematical equation on mathematical logic, such as negations.
Why? Because Apollo is the god of mathematics and I think it would be funny if Grover and Meg were standing there, staring with horror at:
"What is this nonsense?" Asks Meg, a literal sixth grader who has never before encountered college-level math.
"I...I don't know!" Responds Grover, anxiously wringing his hands. He also has never come across something like this before. "I never went to high school!"
"Is it code for something?"
"The little carrot there looks kinda like a Greek Delta- is Daedalus related somehow?"
"The carrot!" Grover points at the symbol between the 'p' and 'q'. "It looks like the Delta symbol!"
The sentence below the odd thing reads;
You can find me in education,
"...What does that mean?" Grover whimpers.
"...negation," Apollo's staring at the strange equation. "'Solve my riddle, or play second fiddle. You can find me in education, for I am the negation!'. That's the missing word in the rhyme."
They stare at him. "How do you know that?" Grover bewilderedly asks. "It makes no sense!"
"Math logic," Apollo simply says. "This particular one is...about first, second-year level in college, I'd say."
Grover closes his eyes, muttering; "No wonder I couldn't solve it." as Meg stares first at the equation, then at Apollo.
"What even is a negation?"
"That," Apollo points to the squiggly lines. "It cancels the truth values out, giving you the opposite of what's inside the parathesis."
Apollo huffs. "The 'p' and 'q' both represent something, like two parts of a sentence. The carrot can be upside-down or right-side-up, representing 'or' or 'and' in that sentence."
"Which way is up when?" Grover looked to be on the verge of tears as the realization math did not, in fact, end with numbers or numbers and letters.
"Uh..." Apollo made a 'V' with his hands. "If it's like this, it's 'or'. If it's like this," he made a tiny pyramid with his hands. "It's 'and'. Imagine a line through the center, like an 'A'. That's 'and'."
Grover rubbed at his eyes. "Too much," he whimpered. "Too much."
Apollo gave him an awkward pat on the shoulder. "In this case," he said. "It's saying 'and'. The negation, well, negates their values, so it becomes-" he pats his pants and looks in his pockets. "Anyone have a pen and paper...?"
Blank looks met his. "Okay, then...then just imagine a squiggly line in front of the 'p' and 'q'. That's what the first negation does. Then the second one negates that negation, taking the squiggly lines away."
Breathing in, he finished with; "So our mathematical answer would be, 'p and q', written with the carrot right-side-up- like the 'A'."
Then it was broken. "How do you know all that?" Meg demanded, looking extremely confused. "That makes no sense. I thought there were numbers."
"There are," Apollo patiently explained. "But this is a logic problem, and they don't do numbers."
"Never before have I been grateful to not to have to go to college," Grover rubbed at his temples. "Algebra was bad enough. Now this?"
"Hey!" Apollo looked slightly offended. "It's all quite fun, really, when you figure it out! Besides, we didn't even have to solve it!"
"Then why did you?" Meg asked.
Apollo stared at her. "Because you asked me too-!"
"Nope." She blew a raspberry. "None of us did."
He closed his eyes, as if praying for mercy.
"Anyway," Apollo gave both of them the stink-eye. "Math and music were quite intertwined back in the day, so the Muses and I are quite adept at it- Thalia's the geometry queen, and whatever you do, do not say 'Bet you can't solve this in a minute' to Urania. She will make you look stupid."
"ANYWAY," Apollo gives her the stink-eye. "Ancient Greece was a breeding ground for mathematical minds- Pythagoras, for one, who was my son to boot! Even Hestia enjoys looking over Hephaestus's construction equations in her spare time."
The other two stared at him, as if shocked the gods would find math, of all things, fun.
Apollo awkwardly glanced away from them. He didn't know what their reactions would be if he told them of the many contributions he has made to the world of mathematics. For some reason, silly mortals didn't seem to appreciate the hard work put into them!
Sighing, he said; "Uh, Labyrinth, the answer is 'negation'. We got side-tracked there for a bit."
One hallway in front of them glowed with the answer. Without another word, they quickly speed-walked down the passage-way.