What is the greatest number of tens in 384

If a • b*2 = 1.8 x 10*-7, and c•b/d = 7.2 x 10*-4, find the value of a•d*2/c*2

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

Find the value. a. 0.003 b. 0.03 c. 0.3 d. 3