How many numbers less than 10000 are there whose sum of the digits is less than or equal to 5?
Options:
A .  125
B .  100
C .  126
D .  189
E .  3x2 + 17x – 32
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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