"I've already tried entering these three sets of numbers separately on the keypad. Nothing happened! Entering them all together didn't work either!
"As for patterns, increasing, decreasing, geometric sequences, Fibonacci sequences, recursive sequences... I tried a few of each. None of them worked!" Gu Zheng said.
Song Ning stared at the string of numbers, her mind racing...
"Then we can rule out the mathematical angle. But these numbers only contain ones and threes. There has to be some kind of pattern..."
"Gu Zheng! There's no limit on how many times we can use this keypad, right?"
Gu Zheng shook his head. "I didn't see anything about a limit on attempts."
"Then let me try!"
Song Ning stepped forward, tried entering a few numbers, and pressed the confirm key.
Nothing happened.
She thought for a moment, entered a few more numbers, and pressed confirm again.
Still nothing.
"How many minutes do we have left?"
Gu Zheng checked his watch. "Eight!"
Song Ning furrowed her brows and muttered to herself:
"Don't overcomplicate it! A code like this wouldn't be too complicated!"
She stared at the string of numbers. It had nothing to do with mathematics, nor did it seem related to chemistry or physics. What would be the simplest, most readily understood pattern?
She frowned, stepped forward, and entered another string of numbers.
Once again, she pressed confirm.
This time, something happened.
A mechanical rumbling came from a corner of the storeroom.
A door appeared beside a stack of cardboard boxes.
That was it!
They exchanged a look, delight spreading across both their faces.
Gu Zheng had been standing beside her and had seen Song Ning enter the numbers "132113."
For the moment, he could not figure out the trick behind it at all.
But time was running out, and he had