In reply to Belkar.

Since twenty begins the next digits place, it has two numbers (much like "ten" starts the second digits in our system: 10) There is a single dot, indicating one group of twenty, and the "zero" symbol, indicating nothing in the ones place. The trick is that they write numbers top-to-bottom instad of left-to-right like we do, so it's a single dot over a zero symbol:
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