Question
How many numbers less than 10000 are there whose sum of the digits is less than or equal to 5?
Answer: Option C
:
C
Let the required number be represented as ABCD.
A+B+C+D≤5
Introducing a dummy variable E,
A+B+C+D+E=5
This is the arrangement of 5 zeroes and 4 ones (the number of plus signs). Answer is 9C4=126.
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:
C
Let the required number be represented as ABCD.
A+B+C+D≤5
Introducing a dummy variable E,
A+B+C+D+E=5
This is the arrangement of 5 zeroes and 4 ones (the number of plus signs). Answer is 9C4=126.
Was this answer helpful ?
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