Roman Finger Counting
Cool! I've noticed a similar way of counting that's still quite common today in China. They point with their thumb to each segment of their four fingers to count up to 12 on one hand. The other hand tracks the number of 12 counts, which lets you keep track all the way up to 144 with both hands.Not quite on the level of the Romans, but still a solid improvement over how I've done it my whole life!