Greek & Latin

 Meaning in English
semi-; hemi- 1/2
hen- ; uni- 1
sesqui- 1-1/2
dyo (di-, dis-) ; duo- (bi-, bis-) 2
tri-; tri- 3
tetra-, tessaro- ; quadri- 4
penta-; quinque 5
hex, hexa-; sex- 6
hepta-; septem- 7
octo-; octo- 8
ennea-; novem- 9
deca-; decem- 10
dodeca-; duodecim 12
hecatonta-; centi- 100
chilio-; milli- 1000
myri-, myriad-; any large or countless number