Q: How many combinations are there if there are seven numbers and you have to have a six number combination?

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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.

The number of combinations of six numbers that can be made from seven numbers will depend on if you can repeat numbers. In all there are over 2,000 different numbers that can be made.

8x7x6x5x4x3x2 or 40320 * * * * * That is totally incorrect. There are only 8 combinations: one with each of the 8 numbers missing. In a combination the order does not matter so 1234567 is the same as 1236547 or 7643125 etc.

Start with the factors. Multiply combinations of three prime factors, then combinations of five, then seven, etc. All generated numbers will be guaranteed to have an odd number of prime factors.

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There are 7 combinations. Each combination excludes a different one of the seven numbers.

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.

The number of combinations of six numbers that can be made from seven numbers will depend on if you can repeat numbers. In all there are over 2,000 different numbers that can be made.

8x7x6x5x4x3x2 or 40320 * * * * * That is totally incorrect. There are only 8 combinations: one with each of the 8 numbers missing. In a combination the order does not matter so 1234567 is the same as 1236547 or 7643125 etc.

Start with the factors. Multiply combinations of three prime factors, then combinations of five, then seven, etc. All generated numbers will be guaranteed to have an odd number of prime factors.

There is only one combination. There are many permutations, though.

Revise your question, it makes no sence.

Because every combination is equally probable, but more combinations sum to seven than to any other total. There are 36 possible combinations; of these seven will produce 7, only one will give 2 and only one will give 12.

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Yes seven is a prime number and the only numbers that will go in to seven is one and seven.

any 4 from 7 is 35, in any order is 35 x 24 ie 840

That dependsThat depends upon whether you are allowed to repeat numbers. If you are allowed to repeat, that means that all seven digits (say 1 through 7) can be used in each of the four positions of your combination, even if a digit has been used in another position. That means there are 7 x 7 x 7 x 7 = 74 = 2401 possible combinations for your lock. But if you are not allowed to repeat, that means that every time you pick a digit for one spot, there will be one less digit for the next, and one less for the next, and so on. So, the first number can have seven possibilities, the second can have six, the third can have five, and the last can have four possible digits. That means there are 7 x 6 x 5 x 4 = 840 possible combinations for your lock, only about a third as many.Check out the related link at MathsIsFun. It has very good information on this subject.* * * * *That is true for PERMUTATIONS, but not for combinations. In a combination, the order of digits does not matter so that 1234 is the same as 1342 or 4213 ext.As a result you have 7C4 = 7!/[4!*(7-4)!] = 7*6*5/(3*2*1) = 35 combinations - not 2401.Incidentally, nCr is the notation for the number of combinations of r objects taken from n objects - exactly what the question asked for.