Answer
The year when America declared Independence is \[1776\]
Work Step by Step
The Roman Numeral written along the base of the pyramid at the back of US one dollar is MDCCLXXVI
Converting MDCCLXXVI to Hindu Arabic Numeral, we get
\[\begin{align}
& 1000+500+100+100+50+10+10+5+1=1000+700+70+6 \\
& =1776
\end{align}\]
Which is the year when America declared Independence.
After Observing and calculating the back of US one dollar, we find the year
\[1776\] written in Roman Numerals along the base of the pyramid
