What are the correct values for relativistic 3-momentum $p=mv$?

Question

Is the value of $m$ in this formula relativistic mass or real mass? Just trying to figure out if this is the right equation for my problem.

Answer 1

The four-momentum has $E/c=p^0=\gamma m_0c,\,p^i=\gamma m_0c\beta^i$ if $m_0\ne0$, but $E/c=p^0,\,p^i=E\beta^i$ whether or not $m_0=0$.

Answer 2

p = mv

Is the value of m in this formula relativistic mass or real mass?

In your formula, $m$ is the "relativistic mass," not the rest mass (or "real mass" as you say).

If the rest mass is denoted as $m_0$ then $$ p = \gamma m_0 v\;, $$ where $v=\frac{dx}{dt}$ and $\gamma = 1/\sqrt{1-v^2/c^2}$.