2020 · Q8
If m is the number of prime numbers between 0 and 50; and n is the number of prime numbers between 50 and 100, then what is (m – n) equal to?
Elementary MathematicsNumber System
- A4
- B5
- C6
- D7
Explanation
Primes below 50 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 — fifteen in all, so m = 15. Primes between 50 and 100 are 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 — ten in all, so n = 10. Hence m − n = 5.