How many pieces of 6 inch lap siding would it take to cover a 24ft by 38ft house?

I am figuring on a 12 foot long piece. There will be about 5.5" of exposure. Add up the sides to get the perimeter (24+24+36+36=120 ft) and multiply by the wall height. 120x8=960 square feet of wall. Do not subtract for windows or doors. If there are triangle ends on the roof, multiply the base by the height and divide by 2 (for each end). This will be for a house with 8' walls and gable roof (triangle at each end) with a 4/12 pitch. You will need 200-220 pieces. I have added 15% for waste and the occasional oops. Let me know if this works.

Basically 5 boxes of siding,making sure to keep extras and leftovers for repairs in the future.

A box= 2sq. Siding per.

Accessories and corners extra.

Ken