A circle of trademark paper is pasted around a rectangular biscuit box with a length of 20cm, a width of 15cm and a height of 23cm. The joint part of the trademark paper is 2cm Write the formula and explain the reason

A circle of trademark paper is pasted around a rectangular biscuit box with a length of 20cm, a width of 15cm and a height of 23cm. The joint part of the trademark paper is 2cm Write the formula and explain the reason

Let's calculate the surface area of the cuboid, but we need to calculate the area of four sides instead of two sides,
Area of front and back + area of left and right + area of joint
Length × height × 2 + width × height × 2 + 2 × height
=20×23×2+15×23×2+2×23
=460+690+46
=1196 (square centimeter)