How many grams of sodium chloride are in 3 x 10 to the 25 formula units of sodium chloride?

1 mole NaCl = 58.443g NaCl = 6.022 x 1023 formula units NaCl

3 x 1025 formula units NaCl x 1mol NaCl/6.022 x 1023 formula units NaCl x 58.443g NaCl/mol NaCl = 2911g NaCl = 3000g NaCl (rounded to 1 significant figure)