Letters with odd values — Aptitude Question
Letters with odd values: If A = 1, B = 3, C = 5 and so on, what is the code for I? Answer and worked solution on CodeKairo.
- Topic: Coding & Decoding
- Section: Logical Reasoning
- Difficulty: Medium
- Time target: 60 seconds
Question
If A = 1, B = 3, C = 5 and so on, what is the code for I?
Options
- 15
- 17
- 19
- 21
Show the answer and the worked solution
Correct answer: B. 17
Worked solution
- The values run 1, 3, 5, … so the nth letter is 2n − 1.
- I is the 9th letter, so its value is 2 × 9 − 1 = 17.
Answer: 17.
The idea
Find the position of the letter, then apply the stated rule. Counting the alphabet on your fingers to I is slower than knowing J = 10.
Shortcut. Anchor on E, the 5th letter, whose value is 9. I is four letters after E and each step adds 2, so I = 9 + 8 = 17.
Common trap. "19" — using 2n + 1 instead of 2n − 1 (18 + 1), or counting I as the 10th letter; A = 1 shows the rule takes one away from double the position.