Question

show √6.4 on no. line

Answer 1

first draw the line of 1 cm
and do extent and bisect it into two equal half and mark as c as a center.
now frm b a perpendicular line draw and match it

Answer 2

first draw a line of length 6.4cm and label the enda a and b
then extend it 1cm and label the end c
then bisect the line into halves
and mark the center as o
from the center of the draw a arc from a to c
now from b draw a perpendicular which meets on the arc
marke the point on arc as d
then using a compass
b as center and d as start draw an arc 
 the arc must meet  on a-c 
mark the point on ac as f 
measure b - f is root 6.4