Answer:
Assuming that Samuel's retiring age is exactly 65 years old, and he starts collecting benefits 24 months before his full retirement age (exactly on his birthday number 63), then he will receive $867 per month (or 86.7% of his full benefits).
This calculation varies depending on the number of months, e.g.
months before full retirement age % of full retirement benefit
24 86.7%
23 87.2%
22 87.8%
21 88.3%
20 88.9%
19 89.4%
18 90.0%
17 90.6%
16 91.1%
15 91.7%
14 92.2%
13 92.8%