Question 13 of 36beginner🔧 ApplyShort Answer2 marks

Which of the following numbers are prime? 23, 51, 37, 26

Correct Answer

Step 1: Check 23 Factors of 23: 1, 23 Only two factors ∴ 23 is prime

Step 2: Check 51 51 = 3×173 \times 17 Factors of 51: 1, 3, 17, 51 More than two factors ∴ 51 is composite

Step 3: Check 37 Factors of 37: 1, 37 Only two factors ∴ 37 is prime

Step 4: Check 26 26 = 2×132 \times 13 Factors of 26: 1, 2, 13, 26 More than two factors ∴ 26 is composite

Answer: 23 and 37 are prime numbers.

Exercise: Figure it Out (Section 3) | Q: 4 | (Page Page 8)
For More Understanding

Explanation

A prime number has exactly two factors: 1 and itself. 23 has factors 1 and 23 only (prime). 51 = 3×173 \times 17, so it has factors 1, 3, 17, 51 (composite). 37 has factors 1 and 37 only (prime). 26 = 2×132 \times 13, so it has factors 1, 2, 13, 26 (composite).

Solution Steps

  1. Step 1: Check 23: Factors are 1, 23. Only two factors, so 23 is prime.

  2. Step 2: Check 51: 51 = 3×173 \times 17. Factors are 1, 3, 17, 51. More than two factors, so 51 is composite.

  3. Step 3: Check 37: Factors are 1, 37. Only two factors, so 37 is prime.

  4. Step 4: Check 26: 26 = 2×132 \times 13. Factors are 1, 2, 13, 26. More than two factors, so 26 is composite.

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