I like this concept....
Well, if you started at zero, and aged 54 yrs, your avg age is 27.
I am 46, so my avg age is 23.

This one is getting compicated...for my feeble 54 year old brain, er, 27.2, or 27.9 er whatever...
If you are 50.. you average age would be 25.5.. i just did the math... you add 1+2+3 ect. all the way to 50.. and then divide by 50..

Oh, my...beyond me!
Easier to do the n(n+1)/2 formula