What makes the most sense to you? Counting up from one, or zero?
Look how it pans out visually ... Here's counting from one, in sets of tens.
Here's counting from zero. See the difference? Each row starts a new set, or decade of numbers.
Does this matter? I hear:
No it doesn't. The values are the same. Kids don't care. We all start counting at one.
Then I hear:
Why yes, it does. Look how much more sensible it is to consider all the Twenties together, the Thirties, etc. These groups are like decades (sets of 10 years). We need that zero!
We need that zero. Well some of us do, but some don't. Let's agree to disagree. Which raises a new question: Do we need zeros before the 1, 2, 3?
We do need these zeros if we want our data to be sorted correctly on a computer. Otherwise, 5 will be sorted up into the 50's decade group rather than between 4 and 6. Oops, I mean between 04 and 06. If you've ever lost a file or folder after changing its name, you might look around. It could still be there, but placed with an unexpected set of neighbors.
In computer (and roulette) terms, 0 and 00 are not the same. In math terms, they are the same.