Here are the Greek numbers, which you may find used in English words:
- eis, mia, ev; mono- - 1
- duo; dis (di-) - 2
- treis, tria; tris (tri-) - 3
- tettares, tettara; terakis (tetra-) - 4
- pente; pentakis (penta-) - 5
- hex (hexa-) - 6
- hepta (hepta-) - 7
- octô (octa-) - 8
- ennea - 9
- deca (deca-) - 10
- endeca - 11
- dodeca - 12
- treiskaideca (trideca-) - 13
- tettares kai deca - 14
- pentekaideca - 15
- hekkaideca - 16
- heptakaideca - 17
- oktôkaideca - 18
- enneakaideca - 19
- eicosi (icosa-) - 20
- hecaton - 100
- chilioi, chiliai, chilia - 1000