-8
The factors of 21 that add up to 8 are 1 and 7.
2
The two factors that multiply to 0.0625 and add up to 1 are 0.25 and 0.25. When you multiply 0.25 by 0.25, you get 0.0625, and when you add them together, 0.25 plus 0.25 equals 0.5. However, if you are looking for two different factors, they are approximately 0.0625 and 0.9375, which multiply to 0.0625 and sum to 1.
268
-1005
167
The factors of 8 are 1, 2, 4, and 8. The factors that add up to 10 are 2 and 8.
Factors of 250 that add up to 8 = 1 + 2 + 5
47
212
1012
1510