The city launched its “pass-through allowance” program in April.

Apparently, something invisible yet undeniably real passes through our homes by the trillions every single second — straight through walls, roofs, and human bodies alike, without so much as slowing down. The city announced it would pay a monthly stipend based on the number of particles counted.

My son’s cram school had just raised its fees. So I went to the information session.

The detector they handed out was a white box about the size of a palm, its LCD screen showing numbers that never stopped moving. The staff member said, “Just set it somewhere and keep a record.” So that same evening, I put it on the shelf in the living room.

I had imagined the numbers would be a little more manageable.

When I woke up the next morning, the display read 2,417,836,000,000. About 2.4 trillion. And it kept climbing while I watched. I opened a blank page in my household ledger and started writing down the date and the figure. Every day, without missing one — down to the decimal places.

“Can’t you just eyeball it?”

My son said this while poking at his beef stew.

“Eyeball what?”

“I mean, it’s two trillion. Does the ones place really matter?”

He had a point, I suppose. But I don’t like it when the bank rounds off my balance either. Record it accurately, submit it accurately. That’s all there is to it.

Three months later, I carried a cardboard box stuffed with photocopied ledger pages to the city office. Ninety-two days’ worth. Every entry filled in to two decimal places. The young clerk at the reception desk took the box and blinked.

Two weeks later, the papers came back.

A single red sticky note was attached. “The figures are too precise. For future submissions, please round to an approximate number.”

I wasn’t surprised, exactly. What I was thinking was: when they say “round,” which place do they mean? Trillions? Hundreds of billions? Tens of thousands? The note didn’t say.

I called the city office. The person in charge was away. No callback came.

The next morning, for the first and only time, I unplugged the detector for thirty minutes. Then I opened my ledger to the blank space and wrote:

roughly 2 trillion