Other contributors have said "How many 4 digit numbers can be formed using the set 1 3 5 7 9 with no repetition and numbers must begin and end with an odd digit?" is the same question as "By using the set 1 3 5 7 9 taking any numbers 9 times and addition of numbers must be 30?" If you believe that these are not asking the same thing and should be answered differently,
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