How do you find ppm of sodium using nutrition label?

[ComputersConfuseMe]

Im taking a food chem class and I'm not sure if I'm doing this calculation correctly.
I didn't include the whole label, only the parts that I think I need.

Given the following nutrition label, calculate ppm of sodium.

Serving Size 1 cup (100 g)
Sodium 490 mg


This is how I tried doing it.

First I found the % (w/w) of sodium.
490 mg --> .490 g
(.490 g / 100 g) x 100 = 0.49 %
0.49% sodium

Then use the sodium % to find ppm.
x ppm is (x mg / 1000g)

(x mg/ 1000g) x 100 = 0.49%
Solve for x.
x = 4.9 mg

My answer is 4.9 ppm. Does that sound right?