Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Indo-European
*penkʷēḱomth₂
→
Greek
πενήντα
(inherited)
→
Ancient Greek
πεντήκοντα
(inherited)