A hollow cylindrical iron pipe is 35 cm long. Its outer radius is 12 cm and its inner radius is 10 cm. What is the volume of iron in the pipe, in cubic cm? (Use π = 22/7.)

Iron occupies the shell only: π$(R^2-r^2)h=(22/7)\times (144-100)\times 35=(22/7)\times 44\times 35=4840$ cubic cm. The trap 15840 is the solid outer cylinder π$R^2$$h$, with the bore never removed; 11000 is π$r^2$$h$, the empty bore itself; 440 uses $(R-r{)}^2=4$ in place of $R^2-r^2=44$, and squaring a difference is not the difference of squares.