According to pagat.com's John McLeod, quite a well researched card aficionado, there were four steps in the evolution of Pinochle scoring.
Based on the individual "counter" points in the trick taking phase, A T K Q J were scored respectively:
11-10-4-3-2 (original quinary scoring)
10-10-5-5-0 (ternary scoring)
10-10-10-0-0 (binary scoring)
1-1-1-0-0 (reduced binary scoring)
If playing with 9's, before the most modern evolution, it was worth 10 and was referred to as Dix (pronounced Deese) which is French for 10. Yes, the 9's were called 10's -- blame the French!
Only when the most recent scoring came along were the meld values able to be divided by 10 to stay in sync with trick points. Simplifying the scoring was a necessary evolution to make pinochle more inviting to players.
If you want to learn how to count meld using the most modern scoring, go to Power Pinochle's Meld Calculator and either generate a random hand or build your own. http://www.powerpinochle.com/forum/meld.php