846 = 8*(10**2) + 4*(10**1) + 6*(10**0)

##</code><code>##

units:    ( int($num / (10**0)) ) % 10
tens:     ( int($num / (10**1)) ) % 10
hundreds: ( int($num / (10**2)) ) % 10

##</code><code>##

23 = 1*(2**4) + 0*(2**3) + 1*(2**2) + 1*(2**1) + 1*(2**0)

##</code><code>##

bit 0: ( int($num / (2**0)) ) % 2
bit 1: ( int($num / (2**1)) ) % 2
bit 2: ( int($num / (2**2)) ) % 2
...
bit 7: ( int($num / (2**3)) ) % 2

##</code><code>##

int($i / (2**$j))

##</code><code>##

$i >> $j

##</code><code>##

$k % 2

##</code><code>##

$k & 1

##</code><code>##

bit 0: ( $num >> 0 ) & 1
bit 1: ( $num >> 1 ) & 1
bit 2: ( $num >> 2 ) & 1
...
bit 7: ( $num >> 7 ) & 1

##</code><code>##

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'