Sum is even if number of odd addends is even (since even + even = even, odd + odd = even).
Related Articles
- Total favorable roll sequences (before sum constraint):
- \cdot 9 \cdot 9 = 486
- Now impose the even-sum condition.
- Prime numbers: 2 (even), 3, 5 (odd) → primes: one even (2), two odd
- Non-primes: 1 (odd), 4, 6 (even) → non-primes: one odd (1), two even (4,6)
- We need the total sum to be even, with exactly two prime rolls and two non-prime rolls.
