“Oh no, not again!”

“What’s the problem, Mrs. Clabber?” Caleb asked. 

“The register is 55 cents short!” Mrs. Clabber exclaimed, shaking her head. 

“Can I take a look?” Caleb said. He noticed that the shiny register had the words AUTOCHANGE 2020 marked on the side. 

“This register is new. It dispenses change automatically,” said Mrs. Clabber. “I always have the right amount of change in the drawer at the start of lunch. But by the end, exactly 55 cents are missing!”

“Don’t worry, Mrs. Clabber,” assured Caleb. “I’m on the case!”

The next day, Caleb dashed to lunch. He stood next to the fruit shelf, peering at the register.

Caleb watched the students pay for their lunches. Their change clinked automatically into the register tray. The prices of each item and the change given back added up correctly.

It was five minutes before the bell was about to ring, and everything seemed fine.

“Sure!” Marcie fished in her pocket and pulled out two dimes and two nickels.

“Did you have any coins before lunch?” Caleb asked.

Marcie shook her head. “Nope! Our team is doing a fund-raiser. All of our change goes into the jar in Coach’s office.”

“Aha,” exclaimed Caleb.

Mrs. Clabber had the register open when Caleb came back. “Another 55 cents gone,” she sighed.

“And I know why,” Caleb grinned.

“Why?” asked Mrs. Clabber. 

Caleb nodded at the AUTOCHANGE 2020. 

“Turns out your new register has been making donations to the field hockey fund-raiser! You’ll have to get it reprogrammed, and I can tell you why.”