9
If you don't mind starting off with one or more zeros, then they are
every number from 0000 to 9999. That's 10,000 of them.
If a number can't start with zeros, then it's every number from 1000 to 9999.
That's the same 10,000 with the first 1,000 discarded ... total of 9,000 left.
This question needs clarificatioh. There are 4 one digit number combinations, 16 two digit combinations, ... 4 raised to the n power for n digit combinations.
7
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
There are 840 4-digit combinations without repeating any digit in the combinations.
There are 1140 five digit combinations between numbers 1 and 20.
64
This question needs clarificatioh. There are 4 one digit number combinations, 16 two digit combinations, ... 4 raised to the n power for n digit combinations.
7
1234, 1235 and 1236.
The number of four-digit combinations is 10,000 .Stick a '3' before each of them, and you have all the possible 5-digit combinations that start with 3.There are 10,000 of them. They run from 30,000 to 39,999 .
How many four digit combinations can be made from the number nine? Example, 1+1+2+5=9.
Assuming the digits are not repeated, there are four combinations:123, 124, 134 and 234.
There can be only one combination with four digits. Changing their order gives permutations, NOT combinations.The following are possible combinations:1 digit: 1, 4, 6.2 digit: 11, 14, 16, 463 digit: 114, 116, 146.
There are 15180 combinations.
9
There are 12C4 4 NUMBER combinations. And that equals 12*11*10*9/(4/3/2/1) = 495 combinations. However, some of these, although 4 number combinations consist of 7 digits eg 1, 10, 11, and 12. Are you really sure you want 4-DIGIT combinations?
Number of 7 digit combinations out of the 10 one-digit numbers = 120.