Lin Yu was momentarily stunned when he heard Crow-Man's question.

This was a classic "pool filling" problem that mathematically belonged to elementary school level content.

As expected, Number Eight - the one with the 'Student' profession - wiped water from his face and spoke up.

"A pool filling problem? That's easy! We just need to set time as variable X!" he said somewhat urgently.

Lin Yu shook his head.

No, the difficulty of this problem didn't lie in the mathematical aspect.

Before he could speak, his girlfriend beside him - the 'Doctor' whose ID was "April" - sighed helplessly: "But do you know this room's volume, the water inflow rate, and drainage speed?"

Number Eight froze momentarily: "Ah, right... Examiner, what are those values? You can give hints, right? These should fall under hint parameters!" He looked at Crow-Man anxiously.

Crow-Man was also soaked, his feathers and mask dripping wet. He looked at Number Eight and said: "Caw caw, that's not within 'hint' parameters."

Iron Uncle shook his head at Number Eight. "What you're asking about is precisely this problem's difficulty - why would elementary-level math appear in the Death Game... This is testing our estimation skills."

As he spoke, Iron Uncle had already moved to the room's edge, wading through water to walk its perimeter.

Number Eight and April looked puzzled: "What's this uncle suddenly doing?"

Before Lin Yu could explain, the young female Thief named "Unforgotten" spoke: "I think he's using 'step measurements' to calculate the room's length and width... This uncle wears a hard hat and has the 'Craftsman' profession, so he should be skilled at this."

As Unforgotten spoke, Lin Yu nodded slightly.

While the uncle measured the room, Lin Yu wasn't idle either - he approached Crow-Man.

"May I ask whether the final answer needs minute or second precision - this should be within hint parameters, right?" Lin Yu asked with a smile.

Crow-Man glanced at Lin Yu, shook off some water, and replied:

"Caw caw, let me think... alright, your answer's margin of error should be within five minutes." 

Everyone breathed a sigh of relief at this.

A five-minute margin!

This meant the estimation didn't need extreme precision.

Soon, Iron Uncle completed his circuit and returned. 

"By my estimate, this room is about 9 meters long and 6 meters wide... As for ceiling height..." He reached toward the ceiling: "Judging from this, about 3 meters."

Number Eight immediately blurted out: "Then I know! This classroom's 'volume' should be about 162 cubic meters!" He continued eagerly: "Now we just need the drainage and inflow speeds to calculate!"

As Number Eight spoke, Iron Uncle and April nodded, seemingly considering how to measure the water flow rates.

"If each outlet's speed is consistent, we could catch all water from one outlet in a container, then calculate each outlet's flow rate based on filling time, and with ten outlets total..." April proposed first.

But Unforgotten interrupted: "No need for such trouble. Although five-minute error is allowed, the more estimates we make, the greater final error accumulates..." 

She looked at Iron Uncle: "Uncle, just one question - are you sure the room height is 3 meters? Within 10cm error?"

Iron Uncle nodded confidently: "Though height is harder to measure, based on my experience, the proportion suggests three meters! After so many construction years, my eyes are rulers!"

Unforgotten pulled out her utility knife. 

"This standard utility knife is 15cm long," she said, placing it vertically against the wall with the tip touching water and blade snug in the corner. "We just need to time how long until water submerges it completely... then multiply by 20 for total estimated time."

She began counting: "1, 2, 3..."

Iron Uncle immediately understood. 

"Transforming the problem into water rise speed is brilliant... I have this 'pocket watch' item I obtained - let's use it for precise timing!" 

He joined by the wall, taking out a pocket watch to time properly.

April and Number Eight also grasped Unforgotten's method, showing admiration.

"So that's how... this way we can estimate fairly accurately," April murmured. "I overlooked this approach."

Number Eight pouted: "Thought it was a math problem, turns out it's a brain teaser letting this 'Thief' show off." 

April jabbed his waist disapprovingly: "Watch your words! Stop saving face with thoughtless comments!" Her tone carried displeasure.

Chastised, Number Eight awkwardly rubbed his nose and squatted down. 

"Eye-level observation might be more accurate. I'll help watch when the water passes the mark."

Observing the group timing the water rise, Lin Yu instead felt something was off.

As "Iron Uncle" initially said, simple elementary math wouldn't appear in the Death Game.

At first they thought the difficulty was "estimating all parameters."

But after Unforgotten simplified everything to just "water level" plus Crow-Man's allowed "five-minute" margin...

This problem seemed too easy!

But what if viewed differently?

Like Number Eight said, if this wasn't logic/math but a "brain teaser"?

Brain teasers' hallmark is their "traps."

Moreover, Crow-Man clearly wasn't some mechanical NPC reciting rules - it possessed high intelligence and independent will.

It could "judge" which questions to answer between his and Number Eight's.

Yet...

Crow-Man's earlier reply made Lin Yu sense something odd in its tone.

"Let me think", "then", "alright" - three uncertain, imprecise phrases in one "hint" answer about "answer rules."

Crow-Man didn't seem to care about the "error margin," just casually saying five minutes!

In fact, Crow-Man not stating the "margin" initially already struck Lin Yu as strange.

With these thoughts, Lin Yu approached Crow-Man again.