Also, to find out how many pounds = 128 grams, you can set up a ratio:

1 pound : 453.6 grams :: x pound : 128 grams.  Same as 1/453.6 = x/128

Multiply both sides by 128:  128/453.6 = x

Do the division:  x = 0.282 pounds, or just over 1/4 of a pound, or just over 4 ounces (16 oz in a pound)

To answer your original question, "How many cups of sliced carrots makes a pound?":  Since 1 cup is just over 1/4 of a pound, then approximately 4 cups of sliced carrots  would be about a pound (and that's a lot to eat at one time :-)

Given your approximation of 1 cup = 128.0 grams:

1 pound X 453.6 grams/1 pound X 1 cup/128.0 grams = 3.544 cups