"septante", "octante", "nonante" would be coherently based on Latin etymons, but if you want to coherently use "heptante", which relies on a Greek etymon, you s

"septante", "octante", "nonante" would be coherently based on Latin etymons, but if you want to coherently use "heptante", which relies on a Greek etymon, you should probably also use "ennéante" in lieu of "nonante".