There was a short story to go with it. Guess eight year old me had a better memory. I had to Google for the bits I couldn't remember

There once was a girl with 69 boobs. That's 2 2 2 many boobs. On 51st street, she went to Dr. X and he 8 them all. She came out boobless.

I spotted the omission immediately and I knew that the moment had finally arrived: I used something that I learned in math class.

Yep, boobless, aka 55378008. Sibling story is correct, but another reason for boobless is it used all 8 digits of the calculator.

In my junior-high classes, it was something of a tease for the unfortunate late bloomers. Kids at that age are total assholes.