That's a supply of 5 digits . . . 2, 3, 4, 5, and 6.
If the order of the four makes a difference, then there are (5 x 4 x 3 x 2) = 120 ways
to select and arrange 4 out of the 5 digits.
If the order doesn't matter, and you just want to know how many different groups of 4
can be selected out of the 5 you have, then there are only 5 of those.
2 to the 7th power = 128 * * * * * No. That is the total number of combinations, consisting of any number of elements. The number of 2 number combinations is 7*6/2 = 21
There are 9C2 = 9*8/(2*1) = 36 2-digit combinations.
14 * * * * * Wrong! There are 15. 4 combinations of 1 number, 6 combinations of 2 number, 4 combinations of 3 numbers, and 1 combination of 4 numbers.
Six * * * * * No, that is the number of PERMUTATIONS (not combinations). With 3 numbers, the number of combinations, including the null combination, is 23 = 8. With the three numbers 1,2 and 3, these would be {None of them}, {1), {2), {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}.
72
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.
2 to the 7th power = 128 * * * * * No. That is the total number of combinations, consisting of any number of elements. The number of 2 number combinations is 7*6/2 = 21
There are 45 combinations.
There are 9C2 = 9*8/(2*1) = 36 2-digit combinations.
14 * * * * * Wrong! There are 15. 4 combinations of 1 number, 6 combinations of 2 number, 4 combinations of 3 numbers, and 1 combination of 4 numbers.
Six * * * * * No, that is the number of PERMUTATIONS (not combinations). With 3 numbers, the number of combinations, including the null combination, is 23 = 8. With the three numbers 1,2 and 3, these would be {None of them}, {1), {2), {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}.
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.
72
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.
The rearrangement of 5 figure numbers will be 5x4x3x2x1 which is 120 combinations, when you don't repeat a number.
all numbers have to be different 720 360 (6*5*4*3*2*1), * * * * * Wrong. Combinations do not have to be different. Those are permutations. There are only 6C4 = 6*5/(2*1) = 15 combinations.
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