ISRO Computer Science (CSE) 2025 - Question 62

All ISRO Computer Science (CSE) papers | ISRO Computer Science (CSE) 2025

Topic: Discrete Mathematics

How many four letter words can be formed using the letters of the word 'GAGANYAAN' with no repetition of letter?

  • A. 3024
  • B. 192
  • C. 64
  • D. 24

Answer: D. 24

Explanation: The word 'GAGANYAAN' contains 9 letters in total, but only 4 distinct letters: {G, A, N, Y}. We need to form a 4-letter word with NO repetition. Since there are exactly 4 distinct letters available, we must use all 4 of them (G, A, N, Y) exactly once. The number of ways to arrange 4 distinct letters is $4! = 4 \times 3 \times 2 \times 1 = 24$.

| | All questions of ISRO Computer Science (CSE) 2025