octodecimal => base(8)
decimal => base(10)
hexadecimal => base(16)

$base(number,10,16)
change a decimal number into hexadecimal

$base(number,16,10)
change a hexadecimal number into decimal

longip is calculated as follows:

ip: ddd.ccc.bbb.aaa

a + (b * 2^8) + (c * 2^16) + (d * 2^24)