do you mean? the length is 4.5; the height is 0.4 and the width is 5.6?
well... to get the surface area of the closed rectangular prism,
get the sum of the product of: ( L x W x 2 ) + ( L x H x 2 ) + ( W x H x 2 )
substitute the given measurements:
(4.5 x 5.6 x 2) + (4.5 x 0.4 x 2) + (5,6 x 0.4 x 2)
50.4 + 3.6 + 4.48 = 58.48 square units