How Does It Work

[ImLostAgain]

I've put this in this section because I really can't remember how this is worked out.
This is how it was presented 'by a bloke down the pub' who is doing some kind of a quiz and I know it's a single number but I don't know the number or the workings. I put it down to age and stupidity!!

Units digit of the sum of all digits in both dates 1916 & 1991 = ?

[Cloverjo]

The sum of all digits in those numbers is 37, so the units digit is 7.

[Lie-in King]

The same Q (nearly) comes up on a Geocaching site -

http://tinyurl.com/gq8shko

^Stage 3

Apologies if this is of no use.

[Lie-in King]

Cloverjo's answer seems much more reasonable :-)

[ImLostAgain]

Ok then the answer is 7....but how?? I can't remember how to come to this conclusion.
Lie in king, thanks for that but it's all gobbledygook to me.

[Old_Geezer]

1 + 8 + 1 + 6 + 1 + 9 + 9 + 1 = 37

3 is the tens figure
7 is the units figure

Damned tech strikes again

[ImLostAgain]

Ah ok. I've read that link again and suddenly the penny drops.
Thanks to both of you.

[Old_Geezer]

It seems every time I type 9 it put in 8 !!!!!!!!!

1 + 9 + 1 + 6 + 1 + 9 + 9 + 1 = 37

3 is the tens figure
7 is the units figure

[ImLostAgain]

Cheerrs O_G, you just beat me to it.