1+1+1=1?

In the context of a Frame-esque perspectival account of assurance, Dr Field claims that 1+1+1=1.

This obviously has explanatory usefulness when thinking about things Trinitarian, but it seems to me to have the disadvantage that, as far as I know and not to put too fine a point on it, it’s not true.

Why not say 1x1x1=1, which I believe is true?

Of course this still has the disadvantage that 1x1 and 1x1x1x1 also equal 1, but then there are similar difficulties for 1+1 and 1+1+1+1, aren’t there?

Can a mathmo tell is something boffiny about this?