When our daughter, Kelly, was little, Steve and I told her about Santa.

We explained that Santa’s elves spend the whole year making toys, and on Christmas Eve, Santa loads up his sleigh and magically delivers presents to all the good little boys and girls.

When Kelly got older, she started asking questions. She wanted to know how Santa could fit through a tiny chimney. Or how he could visit all the houses in the world in just one night. We answered, “You’ve just gotta believe.”

It was a fun part of childhood. Of course, we knew she’d eventually realize there’s nothing magic about it. She’d figure out the harsh reality: You can’t always get what you want for Christmas. Really, it’s good old mom and dad who do the shopping — and the malls are crowded, toys are expensive, sometimes mom and dad run out of time, or the stores run out of toys.

The average kid stops believing in Santa at about age 7. If they’re smart, they stop believing sooner, at 5 or 6.

If they’re really smart?

They never stop.

I knew Kelly would never stop believing in Santa when she was 6. That was the year she wanted a Barbie cash register for Christmas — the same thing every 6-year-old girl in America wanted.

“What else is on your list?” I asked her. “Because I don’t think Santa’s elves can make enough of those for all the little girls who want one.”

“There’s nothing else on my list,” she answered. “The only thing I’m asking for is a Barbie cash register. That way Santa will know I really, really want one — more than anybody.”

“But none of the stores have them. They’re all sold out!”

“Mom, you’ve just gotta believe.”

Uh oh, I thought, as a bead of sweat ran down my neck.

After launching a massive effort to locate a Barbie cash register, we lucked out. The sister of our neighbor’s cousin’s mailman’s wife found a solitary Barbie cash register, accidentally stashed behind the “Barbie Dream House” display at the K-Mart in Boise, Idaho.

It arrived via FedEx on Dec. 24. I was overcome with relief as I held the package. I hadn’t worked that hard on a delivery since giving birth.

On Christmas morning, Kelly raced out to the living room. When she spied the pink box in front of the fireplace, she squealed with delight. Then she grabbed it and danced around the room with it held high above her head. “I told you!” she cried. “I knew Santa would bring my Barbie cash register!”

You’ve just gotta believe.