The pronunciation of the French words “six” (6) and “dix” (10) is a bit unusual. There are three ways of pronouncing the final “x.”

When counting, eg from 1 to 10, “six” is pronounced SEESS and “dix” is pronounced DEESS. So the last letter sounds like a soft “s” sound.

When saying something like “six apples” (six pommes) in French, the “x” in “six” becomes silent, so it sounds like SEE POM. Ten apples would be DEE POM (dix pommes). That’s because the word for apples (“pommes”) starts with a consonant, the letter “p.” We prefer not to pronounce too many consonants in a row in French, because that interrupts the “flux sonore,” the sound flow.

When you are listing a quantity of an item that starts with a vowel or a silent h (“h muet”), the “x” at the end of “six” or “dix” changes to a “z” sound. So “six trees” would be “six arbres,” pronounced SEE ZAR BRER. “Ten trees” would be “dix arbres,” pronounced DEE ZAR BRER.