CA Foundation · Quantitative Aptitude · Permutations and Combinations
How many 3-digit even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 if repetition of digits is allowed?
There are 108 such numbers. The units place must hold an even digit (2, 4 or 6), giving 3 choices, while the tens and hundreds places each have 6 choices since repetition is allowed. Multiplying gives 6 × 6 × 3 = 108.
- A108Correct
- B72
- C90
- D216
Explanation
The units digit must be even: 2, 4 or 6, giving 3 choices. The tens digit has 6 choices and the hundreds digit has 6 choices. Total = 6 × 6 × 3 = 108. Option 216 is all 3-digit numbers (6×6×6) without the even condition.
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