Why can two conversion factors be written for an equality such as 1 m = 100 cm?

Write the equality and two conversion factors for each of the following pairs of units:

b. nanograms and grams

Write the equality and two conversion factors for each of the following pairs of units:

a. centimeters and inches

Write the equality and two conversion factors, and identify the numbers as exact or give the number of significant figures for each of the following:

b. The Daily Value (DV) for selenium is 70. mcg.

Write an equality and two conversion factors for each of the following medications:

b. 0.25 g of Lanoxin per 1 tablet of Lanoxin

Write an equality and two conversion factors for each of the following medications:

a. 10 mg of Atarax per 5 mL of Atarax syrup

At Sandra's clinic, the medications in a. to d. are used. Write the equality and two conversion factors, and identify the numbers as exact or give the number of significant figures for each:

a. The label on a bottle reads 10 mg of furosemide per 1 mL.

At Sandra's clinic, the medications in a. to d. are used. Write the equality and two conversion factors, and identify the numbers as exact or give the number of significant figures for each:

b. The Daily Value (DV) for selenium is 70. mcg.