There are 1140 5 digit combinations from 1 to 20. 20 combination 3 computes that.
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 are 5,461,512 such combinations.
100
44
There are 1140 five digit combinations between numbers 1 and 20.
There are 1140 5 digit combinations from 1 to 20. 20 combination 3 computes that.
There are 167960 9 digits combinations between numbers 1 and 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 are 5,461,512 such combinations.
There are 840 4-digit combinations without repeating any digit in the combinations.
Just 1.
The answer will depend on how many digits there are in each of the 30 numbers. If the 30 numbers are all 6-digit numbers then the answer is NONE! If the 30 numbers are the first 30 counting numbers then there are 126 combinations of five 1-digit numbers, 1764 combinations of three 1-digit numbers and one 2-digit number, and 1710 combinations of one 1-digit number and two 2-digit numbers. That makes a total of 3600 5-digit combinations.
7
100
How many four digit combinations can be made from the number nine? Example, 1+1+2+5=9.
44