two
Starting with three different letters, six two-letter combinations can be made, if the order of the two letters is important. Only three combinations can be made if the order of the two letters is not important. Example: ABC AB AC BA BC CA CB - six variations But if (for your purposes) BA is the same as AB, Then there are only three: AB AC BC
4435236.. I think
-8
32C3 = 4960
two
10
2600
Starting with three different letters, six two-letter combinations can be made, if the order of the two letters is important. Only three combinations can be made if the order of the two letters is not important. Example: ABC AB AC BA BC CA CB - six variations But if (for your purposes) BA is the same as AB, Then there are only three: AB AC BC
4435236.. I think
Two . . . . . 38 and 83.
16 x 15 / 2 ie 120
There are many different combinations. One example is two and 31.
Simple enough to solve. The answer is a power of two. Assuming you have two possible digits, say for example, 3 and 4, then you simply have to multiply it by how many numbers you want to get the total number of combinations. Each number can be 3 or 4 in this case, and you have 5 numbers. That's two to the fifth. Five combinations of any two numbers. 2x2x2x2x2. The answer is 32 combinations.
-8
32C3 = 4960
There is 1 combination of all ten numbers, 10 combinations of one number and of nine numbers, 45 combinations of two or eight numbers, 120 combinations of three or seven numbers, 210 combinations of four or six numbers and 252 combinations of five numbers. That is 1023 = 210 - 1 in total.