How many different arrangements are possible with 3 digits numbers from 1-9 if we have to arrange them in ascending order?

Question

if there are numbers 1,2,3,4,5,6,7,8,9 how many different three digit values we can make such that the digits are in ascending order? since there are numbers from 1-9, I understand that the first digit should be from 1-7 So like that the different arrangements I found are, 123 234 345 456 567 678 789 even though I have arranged these I am confused with finding all the combinations here. they have given the answer as 84.

Answer 1

Pick any $3$ numbers out of these $9$ numbers and arrange them in ascending order. So there are $9\choose 3$ possibilities.