word Math issue, math homework help

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.

a. 200,000×100

b. 5.2 million ×2.6 thousand

c. 4×10^9÷(1.7 x 10^6)

The approximate value of 200,000×100 is

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