1.) It took Beethoven (the composer, not the dog from that movie) 4.5 years to compose the Ninth Symphony (this may not be true, I made it up). How many decades did it take him?

Question

3.) Michael bought a pumpkin that had a mass of 18,165 grams. What was the mass of the pumpkin in hectograms?

5.) Oscar had 0.874 grams of trash in his house. How many centigrams of trash did he have?
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I'm confused on how to show my work to arrive to my answer. Is there a method in which I could arrive to my answer for each question.

Answer 1

1.
4.5 years x (1 decade/10 years) = ? decades.

3.
18,165 g x (1 hg/100 g) = ? hg

5.
0.874 g x (100 cg/g)