Plz help and thnks...How many significant digits are in each of the following?

Question

1)48

2)306.5

3)0.0000456

4)0.0004560

5)10000

6)300.0

7)85.45

8)3.0 x 10^5

9)75.50

10)30101

Answer 1

1)2

2)4

3)3

4)4

5)5

6)4

7)4

8)2

9)4

10)5

Answer 2

1)48 = 2

2)306.5 = 4

3)0.0000456 = 3

4)0.0004560 = 4

5)10000 = 1

6)300.0 = 4

7)85.45 = 4

8)3.0 x 10^5 = 2

9)75.50 = 4

10)30101 = 5

Those should all be right. i just learned that last week in chemistry.