Charlie's eraser has a mass of 9 grams. how many milligrams is the eraser?

9000 milligrams

Step-by-step explanation:

One gram is the equivalent of 1000 milligrams.

So, 9 grams is 9*1000 milligrams, which is 9000 milligrams.

1,407.5 hours

step-by-step explanation:

we first convert all the time to hours and then sum them up.

there are 24 hours in 1 day, in 58 days, there are 24 x 58 = 1,392 hours.

there are 60 minutes in 1 hour, thus, 30 minutes will be equivalent to 30 / 60 = 0.5 hours.

therefore, the number of hours it will take mercury to complete a full rotation is 1,392 + 15 + 0.5 = 1,407.5 hours