This is the 208th most frequent French word.
total
Complete; entire; whole.
Here, 'total' is used as an adjective to describe the noun 'coût', indicating the complete amount or sum of the cost.
Le coût total de vos achats s'élève à 150 euros.
The total cost of your purchases is 150 euros.
In this sentence, 'totalement' is an adverb derived from 'total', used to emphasize full and complete agreement.
Je suis totalement d'accord avec votre opinion.
I totally agree with your opinion.
Similar to the first example, 'total' in this context acts as an adjective qualifying the noun 'nombre', again expressing completeness or entirety.