Answer:
$793.80
Explanation:
You want to calculate the interest on $630 at 6.5% interest per year after 4 year(s). 
The formula we'll use for this is the simple interest formula, or:
 I = P x r x t
Where: 
 
P is the principal amount, $630.00. 
r is the interest rate, 6.5% per year, or in decimal form, 6.5/100=0.065. 
t is the time involved, 4....year(s) time periods. 
So, t is 4....year time periods. 
To find the simple interest, we multiply 630 × 0.065 × 4 to get that: 
 
The interest is: $163.80 
Usually now, the interest is added onto the principal to figure some new amount after 4 year(s), 
or 630.00 + 163.80 = 793.80. For example: 
 
If you borrowed the $630.00, you would now owe $793.80 
If you loaned someone $630.00, you would now be due $793.80 
If owned something, like a $630.00 bond, it would be worth $793.80 now.