<prompt> Human: I am graduating college biomedical engineering and my parents gave me several paper US Savings Bonds EE which they had purchased for me years ago. Im really confused as to how the interest rates works for these bonds; is it static or do they vary? Is it generally worth in to hold onto these bonds until theyve reached full maturity? The bonds are as follows:Face Value - Issue Date200 - 1094200 - 0500100 - 050075 - 050050 - 0606  <response>: You can calculate their current value here: My grandmother passed away in December and we found some 50 bonds that were purchased in 1970 for about 37 each and are now worth around 270 each. 