One (Upper left)
3*2 + 7 = 13
Two
3*7 + 2 = 23
Four
(8 * 2) / 4
Three
8 - (4/2) Sorry I mixed them up.
Five
(10/5) + 5 = 7
Six
10/(5 + 5)
Seven
(16/4) * 3 = 12
Eight
16 - 4*3