Addition Tricks (4)

$\large \begin{aligned} \displaystyle \sum_{n=0}^4 3^n &= \dfrac{3^5 - 1}{3-1}\\ &=\dfrac{242}{2}\\ &=\boxed{121} \end{aligned}$

Sum of first 5 non-negative powers of 3 = $3^0 + 3^1 + 3^2 + 3^3 + 3^4\\ = 1 + 3 + 9 + 27 + 81\\ = \boxed{121}$

The first 5 non-negative powers of 3, form a G.P. Thus their sum will be

$\dfrac{3^5 -1}{3-1}$ $= \boxed{121}$

$3^0+3+3^2+3^3+3^4=1+3(1+3(1+3(1+3)))=1+3\cdot 40=121$