what does -1.09e-7 equate to?

If it is a part of a calculator dispaly it probably means

 

 -1.09e-7

 

\(-1.09\times 10^{-7}=\frac{-1.09}{10^7}=-0.000000109\)

 

But then again e could be Euler's number which is aapprox 2.7182818284590452353602874713527

 

so maybe

\(-1.09e^{-7}=\frac{-1.07}{e^7}\)

 

-1.09/e^7 = -0.0009939513424544

what is -1.09e-7 mean.

 

It is computer language for scientific notation. "e" stands for "exponent of" =10, and "-" means the exponent of 7 in negative. So, -1.09e-7 = -(1.09 x 10^-7) = -0.000000109.