I think your question has a mistake.
Its root 4.5 on the number line.
If it is 4.5 just take the number line and mark it.
The steps for root4.5 is given below.
To draw √4.5 on a no. line. Draw a line segment AB. on it mark point C at a distance of 4.5 cm and point D at a distance of (4.5+1) 5.5cm. now draw the perpendicular bisector of AD and name the point obtained as O. by taking OD as radius draw a semicircle from point O. now from point C draw an angle of 90° and name the point on which the line meets the semicircle as E. now from the needle of compass on C and taking the distance CE draw an arc on line segment AB. the point obtained will be √4.5
Hope you got the idea