kinetic formula question

Question

The formula is $K = \frac{1}{2}mv^2$.

Which part is the square supposed to influence? Does it affect just $v$, $mv$ or $\frac{1}{2}mv$?

The problem is $\frac{1}{2} (1.2\cdot 10^5 [kg]) \cdot 40.8^2 \left[\frac{m}{s}\right]$. How would this resolve?

Answer 1

One has $$ \frac 12 mv^2=\frac 12 m\cdot v\cdot v\ne\frac 12 (mv)^2=\frac 12 mv \cdot mv=\frac 12 m^2 \cdot v^2 $$ giving here $$ K=\frac 12 \cdot 1.2 \cdot 10^5 \cdot (40.8)^2=\cdots, $$ hope you can finish it.