Basic Error in Sound Calcs?

[ReverseEntropy]

My reference, by noted authorities Don and Carolyn Davis, claim there are two methods to find dB-PWL (sometimes called Lw). I find the methods differ by 10dB. What's up?
(Ref: "Sound System Engineering", 1st ed, 12th printing 1986, p.40)

a) Lw = 10 log (watts/watts ref)
b) Lw = 10 log (watts) + 120 dB
For:
watts = 1 W and watts ref = 10e-12, I find:
Equation (a) = 110 dB
Equation (b) = 120 dB

I believe my math is correct. Is this an error by the author?
Thanks for any ideas/suggestions.

 

[ReverseEntropy]

Oh, I embarrased as I have found my mistake. I entered 10^-12 watts into Excel as 10e-12. This is a pitfall I have somehow always had a mental block on, and it is returning to haunt me here. 10^-12 = 1e-12 <> 10e-12.

Sorry...thanks all for understanding.

 

[Rob45]

I was explaining this distinction to my 6th-grade son just a week ago.
He looked at me as if I were speaking Martian...