Help with Significant Figure Calculations homework

Okay, for my first part it says Solve the following mathematical problems such that the answers have the correct number of significant figures.

1) 334.54 grams + 198 grams =
2) 34.1 grams / 1.1 mL =
3) 2.11 x 10^3 joules / 34 seconds =
4) 0.0010 meters - 0.11 m =
5) 349 cm + 1.10 cm + 100 cm =
6) 450 meters / 114 seconds =
7) 298.01 kilograms + 34.112 kilograms =
8) 84 m/s x 31.221 s =

Second part says: Round each of the following to 3 significant figures.
1) 77.0653
2) 6,300,178.2
3) 0.00023350
4) 10.2030
5) 2.895 x 10^21

Third part says: Indicate which zeros are significant and explain why.
1) 10.020
2) 0.0002050
3) 190
4) 270 people in the room

fourth part: Convert each into decimal form.
1) 1.56 x 10^4
2) 5.6 x 10^-2
3) 3.69 x 10^-2
4) 7.369 x 10^5
5) 2.59 x 10^5
6) 4.59 x 10^-1
7) 1.369 x 10^-2
8) 6.9 x 10^4
9) 2.59 x 10^3
10) 2.09 x 10^-3

Please help, I'm so lost right now in chemistry. Though, tommorrow I am going after school to get help from my teacher.

Addition or subtraction:
1) first add or subtract the question.
2) the number of significant figures for the sum or difference must equal the number of sig figs that come after the decimal of the number with the least sig figs after the decimal.

For example:
1) 334.54 + 198 = 532.54
Because 334.54 have 2 sig figs after the decimal, but 198 has no sig figs after the decimal, your answer must have no sig figs after the decimal, so your answer becomes 533 (you round the answer up if the next number is 5 or above)

Multiplication or division
1) First you multiply or divide
2) The answer should have the same amount of sig figs as the number with the least amount of sig figs

For example:
2) 34.1/1.1 = 31
34.1 has 3 sig figs but 1.1 has 2 sig figs, so your answer should have 2 sig figs.

3) 2.11 x 10^3 joules / 34 seconds = 62 J/s (if the number is in scientific notation: 2.11 x 10^3 you only have 3 sig figs, disregard the 10^n)