Should I use plural for 10^6 and 10^9?

All other numbers are simply built up from these. To give a couple of examples:

```
16 Dek ses (one ten and six)
42 Kvardek du (four tens and two)
442 Kvarcent kvardek du (four hundreds, four tens and two)
1,729 Mil sepcent dudek naŭ (one thousand, seven hundreds, two tens and nine)
22,729 Dudek du mil sepcent dudek naŭ (Twenty two thousands, seven hundreds, two tens and nine)
3,022,729 Tri milionoj dudek du mil sepcent dudek naŭ (three millions, twenty two thousands, seven hundreds, two tens and nine)
4,003,022,729 Kvar miliardoj tri milionoj dudek du mil sepcent dudek naŭ (four billions, three millions, twenty two thousands, seven hundreds, two tens and nine)
5,004,003,022,729 Kvin bilionoj kvar miliardoj tri milionoj dudek du mil sepcent dudek naŭ (five trillions, four billions, three millions, twenty two thousands, seven hundreds, two tens and nine)
```

[see](https://en.wikibooks.org/wiki/Esperanto:_A_Complete_and_Comprehensive_Grammar/Numbers)