Tell them it's none of their business. My son apparently shared this information with his best friend since high school, who was also his best man when he finally married at age 40. So what does the friend announce when giving his little speech at the wedding?
Tell NO ONE!
I did tell my second wife. It was a pretty small number since my first wife was my high school sweetheart and I met wife #2 before the divorce of my first wife was final. She told me her number too, which was also pretty small... but over the years she inadvertently mentioned others from time to time. I always got a chuckle out of it, but I think she regretted "getting caught" with that little numbers lie.
The number didn't matter to me, nor did the fact that her count was a little off. Iirc, she was the one who asked about my number first.
I did ask my current wife, just out of curiosity. She answered truthfully... that it was none of my business. I can buy that.