Please estimate the following quantities without using a calculator. Then find a more precise result, using a calculator if necessary. Discuss whether the approximation technique worked.(Use scientific notation. Use the multiplication symbol in the math palette as needed.)

a.400,000 x 200 is

b.5.5 million x 3.1 thousand is

c.4 x 10⁹ divided by (1.6 x 10⁶) is

(Use scientific notation. Use the multiplication symbol in the math palette as needed.)