First make a number line from 0 to 6 or so on and name it as MN. Then take a perfect square near 10, it will be 9. therefore the square root of 9 is 3.
Next take 3 cm distance on number line and mark as A and 0 as D now draw a perpendicular from pointA of 1 cm and name it as B.
Now join B and D. Take a rounder. place its one tip on D and other on B and make a arc cutting line MN. The point where it gets cut is known as root 10.