If m and n are prime numbers such that the sum of m and n is greater than 20 and the product of m and n is less than 50, what is a possible value of mn?

Question

I have no idea how to start. sorry

Answer 1

primes: 2,3,5,7,11,13,17,19,23,27,29,31,37,

 

2+19 = 21 > 20, 2*19 = 38 < 50 =====> 2 & 19 work

 

2+23 = 25 > 20, 2*23 = 46 < 50 =====> 2 & 23 work

 

2+27 = 29 > 20, 2*27 = 54 > 50

 

3+19 = 22 > 20, 3*19 = 57 > 50

 

3+17 = 20

 

So there are two answers: 38 and 46.

Answer 2

Hi Julian;

I CORRECTED A MISTAKE AND APOLOGIZE FOR IT!

m+n>20

2+23>20

25>20

(m)(n)<50

(2)(23)<50

46<50