Explanation :
There are some basic metric conversions.
Prefix Multiple of 10
centi 
Kilo 1000
deka 10
milli 
hecto 100
deci 
For example :

Answer:
Astronomers use a method similar to the one you used with your homemade quadrant. Twice the distance to the Sun, divided by the distance to the star (which is unknown so far) is equal to the tangent of the parallax angle of the star.
Because there is no record of all things. As we have partially unknow information, it can never be held as a fact.