Mars has a mass of 642,000,000,000,000,000,000,000 kg. How would scientists express this number in scientific notation?

= 6.42 × 10²²

(scientific notation)

= 6.42e22

(scientific e notation)

= 64.2 × 10²¹

(engineering notation)

(sextillion; prefix zetta- (Z))

= 64200000000000000000000

(real number)

Vendor B

Explanation:

Using letters to represent each vendor and the symbol < to express wich is less expensive the information in the problem can be resumed like this: A<C, B<C, B<D, D<A.

These expressions involving two vendors have at the left the less expensive vendor and at the right, the more expensive, every vendor that appears at the right in one of the relations can't be the less expensive, this disqualifies C, D, and A, then less expensive vendor is B.