CAT 2002 — QA Question 34
Permutation & CombinationEasy
How many numbers between 0 and one million can be formed using 0, 7 and 8?
Answer & solution
Correct answer: 728
- A
486
- B
1086
728
- D
None of these
Solution
Numbers possible with 0, 7, 8:
Possible single-digit numbers = 2
Possible 2-digit numbers = 2 × 3 = 6
Possible 3-digit numbers = 2 × 3 × 3 = 18
Possible 4-digit numbers = 2 × 33 = 54
Possible 5-digit numbers = 2 × 34 = 162
Possible 6-digit numbers = 2 × 35 = 486
Total possible numbers = 486 + 162 + 54 + 18 + 6 + 2 = 728
Hence, option (c).