On a test, if 80 questions are answered and 42% of them are correct, what is the number of correct answers

What is the number 321,000,000 in scientific notation? also what is the number? ?

Moira has a canvas that is 8 inches by 10 inches. she wants to paint a line diagonally from the top left corner to the bottom right corner. approximately how long will the diagonal line be?

The midpoints of the sides of the large square are joined to form a smaller square. what is the area of the smaller square