Mechanica of Heron EFs

While rereading Ancient Magic a few nights ago (I wanted to design a hedge wizard for an encounter) I tried recreating the sample mechanica given on page 81 using the formula ((Magnitude of Effect x3) + Size - Ease of Use).

None of my attempts yielded the book values. Therefore, if anyone knows what I'm doing wrong please let me know.

My values were:
Quench the Flames: Magnitude 4x3 = 12 (-3 wagon sized) = 9.
Beguile the Gathering: Magnitude 6x3 = 18.
Theurge's Trumped: 4x3 = 12.

The book gave 7, 13 and 9 respectively.

Any help would be appreciated,
Gremlin44

I don't see where you have added Size and subtracted Ease of Use in your equations. Perhaps that is where you are going wrong.

Thanks for your response. I also think this is where my problem may lay.

My problem, however, is that based upon my reading of each item's description, only the fire quencher qualified for any those of the modifiers (It is wagon-sized and thus -3 to the final EF).

Furthermore, all the modifiers on that chart are multiples of 3 as is instilled effect, yet only one of three sample items has an EF that is a multiple of three.

Sincerely,
Gremlin44

Well, the non-3-multiple levels could be because none of them have nice even 5-multiple magnitudes, either.

But I can't get the numbers to work properly myself.