Are these answers right? (Scientific Notation and Significant Figures)

Rewrite in scientific notation to three significant figures. (ans. means my answer)

1. 20.48 - ans. 2.04 x 10

2. 50, 492 - ans. 5.04 x 10 square.

3. 0.237 - ans. 2.37 x 10 negative 1

4. 15.0 x 10 square - ans.1.5 x 10

5. 0.1353 x 10 cubed - ans. 1.35 x 10 square

6. 150,000,000 - ans. 150 x 10 to the eighth power.

For the problems written in scientific notation I moved the decimal first, then dropped the access numbers (I'm to only have three significant figures as stated in the instructions), then wrote them in scientific notion. But I'm not sure if that is the right way to do it.

Please help ("-")

1. 2.05 x 10 (you are rounding 4 to 5 because you need 3 sig figs and 8 is greater than 5)

2. 5.05 x 10^4 (ten to the power of 4) (again, the number after 4 is greater than 5 so it is rounded up. also, you are counting the number of places you are moving the decimal, in this case you are moving it 4 places to the left so the power has to be 4)

3. 2.37 x 10^-1 (that one's right :D)

4. 1.50 x 10^3 (they are saying the number is 15.0x10^2 so the actual number is 1500, and if you write that number in sig figs, it becomes 1.50x10^3)

5. 1.35x10^2 is right :D

6. 1.50x10^8 (don't forget the decimal place)

and yes that's a good way to do your scientific notation, move the decimal point to before the first digit, then count your significant figures then drop the other numbers following, always making sure to round.

You have to round the third digit up or down as well, so problem 2 should be 5.05 x 10^2