just substitute twelve in there,” Neela continued. “So it’s two to the twelfth…”
“No idea.” Persey sighed, causing the chalk cloud to ripple before her, further jumbling the dots and digits. “These numbers are all over the place. Fifty-seven, fifty-eight, fifty-nine here. But another sequence starts at three hundred and two, or four thousand and ninety-six—”
“Four thousand and ninety-six,” Neela said at almost the exact same time.
Persey spun toward her. “Is that the answer?”
“Yep.”
“Can’t be a coincidence.” Riot was right beside Persey, though she hadn’t seen him approach. His fingers lightly grazed her hand, trailing down her thumb until he found the piece of chalk she held. “May I?”
“O-of course.” Why does he make me so nervous?
Riot smiled, soft and relaxed despite the danger they all faced, as he pressed the chalk to the dot labeled “4,096.” He drew a line from it to the next one in numerical order. “It’s like a giant connect the dots. Four thousand and ninety-seven, ninety-eight, ninety-nine, five thousand.”
The sequence ended there, with no 5,001, but the line Riot had drawn pointed directly at the second number lock from the top.
Persey waved her hand in front of her face, trying to drive away the thickening dust so she could see the door clearly. “That must be the one we’re supposed to use.”
“You think?” Mackenzie said. Her voice was close, and Persey realized that, despite her protests, she’d left her perch on the desk.
Neela hurried around them and stood in front of the door. “The code to open it must be four thousand and—”
“Don’t!” Persey cried, snatching Neela’s hand away just as she was about to punch in the first number. She thought of Riot’s minor electrocution when he started messing around with the number keys, and the consequences of wrong answers in the ATM booth. What if this was the same, except pressing the wrong code might lead to something bigger than just a tiny shock?
“What else could it be?” Mackenzie asked, exasperated.
“Five thousand and one, for starters,” Riot said, tapping the final connected dot with the piece of chalk. “It’s next in the sequence.”
“Anything else?” Persey asked.
“The crap I found in those desks was all from the year 2000,” Kevin said. “Even the copyright on the Lizzie McGuire notepad.”
“Three options,” Neela said. “Which do we try?”
“I vote for the year!” Kevin said, raising his hand. “It seems like the most ‘escape room–y’ solution.”
Mackenzie stepped up to the pad. “Don’t listen to him. He’s not even supposed to be here. I vote for math girl’s solution.”
For a moment, Persey wondered if it was Mackenzie, not Wes, who was conspiring to kill them off. “That thing is rigged to deliver an electric shock when you touch it,” she said. “Riot only hit one number. What happens to the person who enters an incorrect code?”
Neela leaped away from the door. “Holy cow babies! I could have died.”
Persey was pretty sure that was the intention.
“Wrap some fabric around your hand,” Riot suggested, rolling his sleeve down so it covered his palm. “For protection.”
But Neela shook her head. “That’s a capacitive-sensing screen. Like a cell phone. It’ll only register if the electromagnetic field is interrupted by something conductive.”
“I’m telling you—the year 2000. I’ve got a good feeling.” Kevin turned Neela to face the door. “Try it.”
“I’ll do it.” The words flew out of Persey’s mouth before she even realized what she’d said. What are you doing?
“No!” Neela cried. “Kevin’s right. I…I should be the one to do it. I solved the equation.”
“Which means you’ve already done your part.”
Persey stared at the flat, illuminated number pad. The wrong combination was probably going to fry her like a hush puppy, so she needed to choose carefully.
Four thousand and ninety-six.
Five thousand and one.
Two thousand.
“Choose carefully,” Kevin said. “Please.”
Right. Carefully. Three options. But were those all the clues this room had to offer? Or…
Persey thought of the rooms they’d been in so far—the office, the loft, the collection, Cavethedral. Each had details that when combined together, revealed the exit. Those details had been chosen carefully. And yet here they were in this classroom that was slowly filling with a nontoxic, annoying-but-not-lethal substance. How could it not have a purpose?
“The chalk,” she said, unable to shake the feeling that it was the key to this mystery. “How could it translate into a number of some kind?”
Kevin snorted. “Maybe if we figured out how much all this chalk weighed.”