You would need to find the total surface area of the box excluding that one side, so what you would do is,
Multiply the height and length of the box to get the long side pieces (12*16) you'd do this twice as you have 2 long side pieces needed, next you would
Multiply the width by the height to get the short end pieces (12*10) and you would do this twice again, and lastly you would
Multiply the length and width together to get the large top piece (16*10) which you would only do once.
After multiplying all these you would add them together and would get
(192+192+120+120+160) which would give you 784.
Your answer would be 784 in^2. (784 inches squared)
