Method: $n_1$ * $u_1$ = $n_2$ * $u_2$

If the dimensional formula is [$M^a$ $L^b$ $T^c$], then: $n_2$ = $n_1$ * $\frac{M_1}{M_2}$^a * $\frac{L_1}{L_2}$^b * $\frac{T_1}{T_2}$^c

Example: Convert 1 Joule to CGS units (erg). 1 J = [ML^{2T}^{-2}] $n_2$ = 1 * $\frac{1 kg}{1 g}$^1 * $\frac{1 m}{1 cm}$^2 * $\frac{1 s}{1 s}$^{-2} $n_2$ = 1 * 1000 * 10000 * 1 = 10^7 So 1 J = 10^7 erg

Example: Convert G = 6.67 x 10^{-11} N*$m^2$/$kg^2$ to CGS. [G] = [M^{-1}$$L^{3T}^{-2}] $n_2$ = 6.67 x 10^{-11} * (10^3)^{-1} * (10^2)^3 * 1 = 6.67 x 10^{-11} * 10^{-3} * 10^6 = 6.67 x 10^{-8} So G = 6.67 x 10^{-8} dyne*$cm^2$/$g^2$