The prime numbers up to 70 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, and 67.
2+3+65=70, for one
61, 7, 2
There is an infinite number of prime numbers after 500!
The prime numbers up to 50 are: 2,3,5,7,11,13,17,23,29,31,37,41,43,47.
Prime numbers are those numbers which are only divisible by itself Likewise, 1,3,5,7,11,13,17,19,23,,29,31,37,41,43,47,51,53,57,59. These are the only prime numbers upto 60.
60, 66, 70, 78, 84 and 90.
So the composite numbers won't get all bunched up.
The prime numbers up to 70 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67 so 70 = 2 + 7 + 61
I suggest you look up a table of prime numbers. Any integer treater than one that is not in the table of prime numbers is a composite number.
2,3,5,7,11,13,17,19,23,29,31,37,39,41,43,47,51,53,57,59,61,67,71,73
There are no prime numbers greater than 10 that add up to 29. Since all prime numbers greater than 2 are odd numbers, no two prime numbers greater than 2 can have an even number for their sum.
Look up a table of prime numbers. All those numbers that are not prime, are composite - except 1, which is neither prime nor composite.