There are 8*7/(2*1) = 28 combinations.
There are 11C2 = 11*10/(2*1) = 55 combinations.
There are 21 combinations.
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There are 9C2 = 9*8/(2*1) = 36 2-digit combinations.
You can make 5 combinations of 1 number, 10 combinations of 2 numbers, 10 combinations of 3 numbers, 5 combinations of 4 numbers, and 1 combinations of 5 number. 31 in all.
There are 8*7/(2*1) = 28 combinations.
Only three: 12, 13 and 23. Remember that the combinations 12 and 21 are the same.
Oh, dude, you're making me do math now? Alright, so if you have three numbers and you're asking how many combinations you can make with those three numbers, it's like a little math puzzle. Each number can be used multiple times, so it's like a little party for those numbers. The total number of combinations you can make with three numbers is 27. That's like having 27 different outfits to choose from for a night out, but with numbers.
There are 11C2 = 11*10/(2*1) = 55 combinations.
You would get 4!/2! = 12 combinations.
There are 21 combinations.
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There are 32C3 = 32*31*30/(3*2*1) = 4960 combinations. I do not have the inclination to list them all.
10 * * * * * That is just plain wrong! It depends on how many numbers in each combination but there are 1 combination of 4 numbers out of 4, 4 combinations of 3 numbers out of 4, 6 combinations of 2 numbers out of 4, 4 combinations of 1 number out of 4. A grand total of 15 (= 24-1) combinations.
There are 45 combinations.
There are 233 - 1 = 8,589,934,591 combinations, not including the null combination.