Question

The end-point P of a line-segment PQ is against 4 cm mark and the end-point Q is against the mark indicating 14.8 cm on a ruler. What is the length of the segment PQ?

Answer 1

Extend the line segment QP towards point zero of the ruler and take a point O on the extended line QP corresponding to point zero on the ruler.
From the figure, we can say:
OP = 4 cm and OQ = 14.8 cm
Now,
PQ = OQ − OP
= (14.8 − 4) cm
= 10.8 cm