Question

Express the following numbers as sum of two odd primes
a)36
b)84

Answer 1

There are so many answers possible.

36 = 19 + 17   = 5 + 31 = 23 + 13  =  7 + 29   

84 = 31 + 53  = 47 + 37  =  79 + 5  =  67 + 17  = 43 + 31  = 13 + 71 = 23 + 61

Answer 2

31 + 5 is  sum of two odd primes of 36

79 + 5  is sum of two odd primes of 84  

Given and To find :

To express the number 36 and 84 as sum of two odd primes.

Solution:

This question can be solved using a simple hit and trial method,

Write the all the prime numbers that lie between 1 and 84.

2, 3 ,5 ,7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83.

Now, for expressing 36 as the addition of two odd prime numbers, we can write:

36 = 31 + 5

Similarly for 84, we can write,

84 = 79 + 5

Thus, in this manner all the similar questions can be solved.