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10 000
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NO! That is the number of PERMUTATIONS, not COMBINATIONS. In a combination, the order does not matter so that 1234 is the same as 1432 or 3412 etc.
Assuming the 4 numbers are different, the correct answer is 15 comprising
4 1-digit combinations,
6 2-digit combinations,
4 3-digit combinations and
1 4-digit combination.
Another way to look at it is that the first number can be in a combination or not. With each of these possibilities, the second can be in or out - giving 2*2 = 4 ways so far. With each of these there are two options for the third giving 2*2*2 = 8 combinations so far and then the last number makes it 2*2*2*2 = 16. But one of these combinations contains none of the numbers - each one is not in. Leaving that one out gives the answer 15.
In general, the number of combinations of any size, from n distinct objects is 2n and if you exclude the null combination, it is 2n - 1.
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What is the sum of 65381204?
A sum is made with a combination of several numbers - a single number cannot make a sum.
How many four digit numbers are made of odd number?
If you're asking for 4 digit numbers where all four digits are odd, then the lowest number possible is 1111, and the highest is 9999. You only have 5 digits to work with. The answer is: 54 - 53 = 625 - 125 = 500.Subtract the 5 cubed for the numbers less than 1111, which are not four digits.
How many four digit numbers can be made using 1-2-3-4?
It is a permutation problem (any number can be used repeatedly), it will become 4 x 4 x 4 x 4 = 256 four digit numbers. If each number can only be used once, then the answer is 4 x 3 x 2 x 1 = 24 four digit numbers.
What is the greatest number made with the digits?
All numbers are made with digits and there is no limit on how big they can be. So there is no greatest number.
What two numbers add together to make a cube number?
Cubes of numbers are made by multiplying a number by itself three times.
