It's so common for people to learn counting to ten when they start learning a new language, but as I've already discussed, this type of learning by memorization is actually bad.
What happens is that we create the mental connections between the sounds, so that the words uno, due, tre begin to flow easily together, but the individual words fail to be linked to the numbers they represent. The end result is that you want to tell someone "eight", but since you learned by memorization, you have to stand there counting on your fingers, saying uno, due, tre, quattro... until you get to otto. Then, with a big expression of joy, you say "otto!" while feeling like a fool.
Link the numbers, not the sounds
We encounter numbers all day long, but numbers are among the most strongly linked words in a native language. Even after years of only speaking English, we still find foreigners more comfortably counting in their native languages, and it's the same for us. This is a weakness, and it's important to break it.
The solution is simply to practice! When you dial a phone number, say to yourself the names of the digits as you dial. "Cinque, cinque, cinque, sei, uno, due, sette..." This helps to get you out of the rhythm of saying them always in order.
When paying for something or counting out change, try to count in the language you are studying. For instance, when counting bills, we say "twenty, fourty, fifty, fifty-five, fifty-six...", so try it in Italian, "venti, quaranta, cinquanta, cinquantacinque, cinquantasei..."
Or, here's a really good one that worked well for me when learning Russian. When I solve sudoku puzzles, I mutter the number I am looking for. After only two or three puzzles, I had the digits 0-9 firmly committed to my memory without the limitation of rote memorization!
Want to see my favorite language resources and courses?
I listed them here.
One of the most popular and comprehensive online language courses is currently running a massive Back To School sale on all their language courses and levels.
60% OFF - 4 DAYS ONLY
(they have gift certificates too)LEARN MORE