Question 18
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How many three-digit numbers have all their digits different and in increasing order from left to right (like 158)?
- A 84 Correct
- B 120
- C 72
- D 504
Correct Answer: Option A
Choose any 3 different digits from 1 – 9 (0 cannot be the first digit of an increasing number).
They can be arranged in increasing order in exactly one way.
Count = C(9, 3) = 84
Answer: 84
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