Consider a unit square OABC, with each side 1 unit in length. Then by using pythagoras theorem.
OB=√1+1=√2
Now, transfer this square onto the number line making sure that the vertex O coincides with zero
With O as centre & OB as radius, draw an arc, meeting OX. at P. Then
OB=OP=√2 units
Then, the point P represents
√2 on the number line.
Now draw, BC OB such that BC = 1 unit, join OC. Then
OC=√(√2)2+(1)2=√3 units
With O as centre & OC as radius, draw an arc, meeting OX at Q. Then
OQ=OC=√3 units
Then, the point Q represents
√3 on the number line.