What is the disadvantage in comparing line segments by mere observation?

 In given figure,

Points $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ and $\mathrm{E}$ are collinear such that  $\mathrm{AB}=\mathrm{BC}=\mathrm{CD}=\mathrm{DE}$. Then $\mathrm{AE}=$_____ $\times \mathrm{AB}$.

Look at the figure below.

The number of line segments in this figure is _____.

Which of the following statement is true?

A part of line having two fixed end points is a _____.

In given figure,

Points $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ and $\mathrm{E}$ are collinear such that $\mathrm{AB}=\mathrm{BC}=\mathrm{CD}=\mathrm{DE}$. Then mid point of $\mathrm{CE}$is _____.

The above figure is called a

 A part of a line with two endpoints is called a _____

 In given figure,

Points $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ and $\mathrm{E}$ are collinear such that  $\mathrm{AB}=\mathrm{BC}=\mathrm{CD}=\mathrm{DE}$. Then midpoint of $\mathrm{AE}$ is _____.

You can draw _____ straight line joining two points.

A straight path with two endpoints is _____. (line segment/ray)

A _____ has a definite length. $($line$/$line segment$)$

Fill the blank space by finding the length. The line $PS$, whose length is $6 cm$ is divided into $3$ equal parts. 

$\overline{PQ}+\overline{QR}=$ _____ $\mathrm{cm}$