English, asked by divyadaswani74, 11 months ago

howmany 4 digit numbers exist,such that sum of digits is equal to 7.​

Answers

Answered by 7405413342
0

Answer:Answer to this question is 84

Explanation:

Answered by sumitkaushik4460
1

Answer:

Explanation:

  • As the sum of digits is 7 so it is the question of permutation and combination to distribute n identical item to r persons

    so let a+b+c+d=7
    so (7+4-1)C3
    but a can't be zero as it is a four digit number so b+c+d can't be 7

    (7+4-1)C3 - (7+3-1)C2
    120-36=84

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