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GATE 2026 XH5 (Psychology) – Question 4

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 1 mark · Multiple choice

How many 3-digit numbers can be formed using three distinct single digit prime numbers?

  1. 64
  2. 24
  3. 12
  4. 4

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Correct answer: (B) 24

Explanation

The single-digit primes are 2, 3, 5 and 7, which is 4 primes. A 3-digit number uses three different ones, in order, so there are $4 \times 3 \times 2 = 24$ numbers.