$12 + 8 + 0*10 = 20$
$20 + 10 + 1*10 = 40$
$40 + 12 + 2*10 = 72$
$72 + 14 + 3*10 = 116$
$116 + 16 + 4*10 = 172$
$172 + 18 + 5*10 = 240$
Hence,Next number will be $240$.