In 2015, a company made 2.7×10^11 mailboxes. in 2019, the same company made 3.9×10^12 mailboxes. how many more mailboxes did they make in 2019? (write your answer in scientific notation.)

The diagonals of a quadrilaretral intersect at (-1,4). one of the sides of the quadrilateral is bounded by (2,7) and (-3,5) determine the coordinates of the other side in order for the quadrilaretral to be a square.

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

2.5 milligrams is equivalent to how many grams