Answer
$\sqrt{14}$
Work Step by Step
The distance $d$ from $P_1(x_1,y_1,z_1)$ to $P_2(x_2,y_2,z_2)$ is given by the formula
$d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2}$
Hence, using the formula above gives
$d=\sqrt{(1-0)^2+(-2-0)^2+(3-0)^2}\\
d=\sqrt{1^2+(-2)^2+3^2}\\
d=\sqrt{1+4+9}\\
d=\sqrt{14}$