Check my scientific notation, just a quick look over, possible mistake? Best answer given ASAP.THANKS!?

Question

For some reason I seem to be doubting myself about this stuff, so if you see an error just let me know. Thanks :)

1. 60000 = 6.0 x 10^4

2. 750000 = 7.5 x 10^5

3. 0.06457 = 6.457 x 10^-2

4. (9 x 10^2) + (1 x 10^4) = (.09 x 10^4) + (1.0 x 10^4) = 10900

5. (9 x 10^12) - (8.1 x 10^9) = (9.0 x 10^12) - (.0081 x 10^12) = 8991900000000

6. (3 x 10^-6) - (5 x 10^-7) = (3.0 x 10^-6) - (.5 x 10^-6) = .0000025

7. 3.4cm^3 = .034 L

how many...

8. cubic centimeters are in a liter =

1/100cm^3

They should be alright, so just a quick look over is all thats necessary

Answer 1

There are 1,000 cubic centimeters in a liter and it should be written

" 1 l = 1.0*10^3 cm^3 "

and you should only have 1 '=' per line

ALSO 3.4cm^3 is 0.0034 L not 0.034 L

Answer 2

Don't quite follow the question in number 8, but the others seem about right.