bit 0: ( $num & (1 << 0) ) >> 0  =  ( $num & (1 << 0) ) ? '1' : '0'
bit 1: ( $num & (1 << 1) ) >> 1  =  ( $num & (1 << 1) ) ? '1' : '0'
bit 2: ( $num & (1 << 2) ) >> 2  =  ( $num & (1 << 2) ) ? '1' : '0'
...
bit 7: ( $num & (1 << 7) ) >> 7  =  ( $num & (1 << 7) ) ? '1' : '0'