Every Saturday, Alejandro helped his aunt at her stall near the plaza, weighing rice, wrapping soap, and counting change into customers' hands.
He was eleven, and he'd gotten fast at math. Most totals he could add in his head before his aunt finished bagging the items.
Saturday afternoons were the busiest, and a line had formed at the stall. A woman came up with an armful of items, rice, two cans of beans, a bar of soap, and a bag of chiles, and asked for the total.
Alejandro added it quickly in his head, said a number, and started counting out her change from the money she'd handed over.
Halfway through counting the coins into her palm, something felt off. He stopped, held the coins in his hand, and added the total again in his head, slower this time, one item at a time.
The number was different. He'd added the beans twice.
"Sorry, one moment," Alejandro said, and recounted her change correctly before she'd even noticed anything was wrong.
The woman thanked him and moved on. His aunt, who'd been watching from the side while wrapping another customer's order, caught his eye and gave a small nod.
"You caught it yourself," she said, once the line had thinned out. "That's the part that matters."
That evening, walking home, Alejandro found himself adding up prices in his head just from memory, the rice, the beans, the soap, the chiles, checking his own math again just to be sure. It came out right every time now.