Eleven

My father was an engineer. He loved solving things, and his pasttime was to present me with math problems, enrobed in word problems.

Our birthdays were two days apart - both quiet Leos. Our family celebrated our joint birthdays on the day in-between.

When I turned 15, my father turned 51.
He pulled me aside and said "Our ages are inverses. When in our lives will our ages be inverses again?"

I was no mathematician at 15. I was stumped.

Nor was I at 26, busy with my life, the math problem long put out of my head.

At 37, somehow I remembered it. He would have been 73, and even though it had taken me 22 years, he would have been proud that I'd finally figured it out.

Tomorrow I turn 39, and will be celebrating with friends. The next day - the day in-between birthdays - I'll be thinking about my dad.

I might even do a few math problems, in his honor.
After all, why wait 'til I'm 48?