There are 4845 combinations.
There are infinitely many numbers with 20 factors. yes there is
An infinite number of ways.
There are 20 such cards.
20 is an even number.
55 is the middle number on a number line from 20 to 90.
There are 6C3 = 20 such combinations.
There are 45 combinations.
The number of combinations is 20C5 = 20!/(15!*5!) = 20*19*18*17*16/(5*4*3*2*1) = 15,504
There are: 20C3 = 1140
20
There are 38760 combinations.
20
I am assuming you mean 3-number combinations rather than 3 digit combinations. Otherwise you have to treat 21 as a 2-digit number and equate it to 1-and-2. There are 21C3 combinations = 21*20*19/(3*2*1) = 7980 combinations.
There is only one combination. The order of the digits in combinations makes no difference. They are considered as being different if they are permutations, not combinations.
There are 1140 5 digit combinations from 1 to 20. 20 combination 3 computes that.
There are 1140 five digit combinations between numbers 1 and 20.
There are 167960 9 digits combinations between numbers 1 and 20.