Question

If there are 8 bulbs in the room in how many ways we can turn on the light

Answer 1

let the bulbs be 12345678

then a=(12, 13,14,15,16,17,18,21,23,24,25,26,27,28,31,32,34,35,36,37,38,4142,43,45,46,47,48,51,52,53,54,56,57,58,61,62,633,64,65,67,68,71,72,73,74,75,76,78,81,82,83,84,85,86,87)