Basically, we're trying to find **the distance between (1, 0) (0, 0) x the distance between (2, 1) (0, 0) x the distance between (3, 0) (0, 0) x the distance between (0, 1) (0, 0)**

By using the distance formula, we can find

distance between (1, 0) (0, 0) = 1

distance between (2, 1) (0, 0) = √3

distance between (3, 0) (0, 0) = √5

distance between (0, 1) (0, 0) = 1

$|1| |2i| |3| |i|$ = 1 x √3 x √5 x 1 = √3 x √5 = **√15**