In 1668, sir lsaac newton built ba reflecting telescope. it had a mirror about 3 cm in diameter. the worlds largest telescope is has a mirro

All geniuses are at least a little batty.  It goes with the territory.   LOL

Did he really stick needles in his eye.   OUCH !!

The answer is given by the ratio of the square of their radiuses

So we have

(300)^2 /(1.5)^2  =  40,000 times as large

Chris has used this fact - Thanks Chris.  

For any solid where one is the enlargement of the other. (They are similar figures)

if the lengths are in the ratio   $$a:b$$

then the surface area will be in the ratio    $$a^2:b^2$$

and the volumes will be in the ratio      $$a^3:b^3$$

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In any 2 dimensional shape

if the lengths are in the ratio   $$a:b$$

then the  area will be in the ratio    $$a^2:b^2$$

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IT IS REALLY HANDY TO KNOW THIS!

For all his reputation, Isaac Newton was a bit of a fruitcake.

Sitting under an apple tree when the apples are falling doesn't seem sensible, did he have some sort of death wish ?

 He apparently fancied himself as a bit of an alchemist and spent a fair bit of time trying to find out how to turn lead into gold. He, when investigating the properties of light, was apt to push needles into his eye to change the shape of his eyeball.

He also, reputedly, invented the catflap. He cut a hole in a outhouse door so that his cat could get in and out, and then when the cat had kittens, he cut out a smaller hole for them alongside the first one. 

It's fortunate that he produced some decent results, otherwise history would see him in a different light.