1 if by land,

2 if by sea,

The square root of -1 if you think this whole invasion might be imaginary,

3.14 if you’re pretty sure they’re going to circle around the Charles River,

3.14159 if you’re certain of it,

e if you must deposit a natural log but don’t want to tell everyone,

Any prime number if our nation is one and indivisible,

13 if you think it’s luck has finally ran out,

Any number raised to 0 if they’re landbound but you’re feeling coy,

Belphegor's prime if you feel the nation’s morals are lacking and perhaps we do need the firm hand of a monarch,

7 if Kevin Spacey is still okay,

Planck’s constant if you can know only the size of the army or its speed but not both,

Avogadro’s number if there are a fuck-ton of them and this is going to go poorly,

Your ex’s post address if we’re all going to die and you never should have left her to become a silversmith,

The golden ratio if you could just touch her bodice one last time,

2024 if you’re not sure this whole democracy thing will really work,

c if we all need to get the fuck out of here at the speed of light,

Complex conjugates if you don’t really know what’s happening anymore,

I or Ⅱ if you’re feeling retro,

2^{aleph_0} if they’re coming by a continuum-bending, wormhole-jumping spaceship,

The square root of two if their commander is wearing one of those funny triangular hats,

Nil if a little bit of extra notice won’t really matter because America is inevitable.