This means that the span from 22 BC to 1 BC is:
22 BC – 1 BC = 21 years by subtracting,
but 22 total by counting inclusively.
Here’s a timeline:
Year Count: 22 21 20 … 3 2 1
↑---------------------↑
Birth Death
That range includes all 22 distinct calendar years (listed above), even though both fall within the “BC” era.
It’s important to understand that:
Era labels (BC/AD) aren’t meaningful for age calculations without considering the absence of year zero.
Inclusive counting (counting both endpoints) gives us the correct total.
A Word About Counting Conventions
The difference between inclusive and exclusive counting can be tricky.
In everyday life, if I say:
“I counted from 1 to 10,”
you wouldn’t start at zero—you count:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10 = 10 numbers total.
