Students can write the numbers 0-9 on index cards to do this activity, or you can use the cards from an UNO deck (digit cards only). Students take one of each number (0-9) and lay out the cards in front of them. Students can do this in pairs or individually.
The teacher says a number and the students build that number using the cards in front of them. The teacher can easily do a quick check and redirect any students who may have an incorrect number (in the target language of course). Depending on the level of the students, numbers can go as high as 9 billion. I usually stick to numbers under 100 for beginners or in the hundreds and thousands for more advanced students, but it could be a good challenge to go higher. Just keep in mind that numbers can’t be repeated (22, 336) since there is only one of each digit. Of course, the teacher can provide multiples of each digit, but I find that there are to many cards to manage. It’s great when students get the hang of it and want to say the numbers for their classmates to build.