jeffl,
Look into modulus arithmetic.
=IF(MOD(A1,16)=0,16,MOD(A1,16))
A1 would hold the channel value (17 = 1, 32=16, 20=4, etc.)
The reason for the IF logic is that when the modulus 16 hits 16, 32, 48, 64, etc. it will = 0, however, we want it to be 16 when this case hits.
Kurt