The e notation tells you where to put the decimal point.
e+ means move the decimal point to the right, e- means move left.
So 1.3e+002 would mean 130 and 1.3e-004 would mean 0.00013.
As for adding 0.0000000001 and 3.0001 to get 3.0001000001, that's not going to happen.
Blitz floating point numbers are single precision, about seven digits.
That means 0.0000000001 + 3.0001 = 3.0001, the first number is simply too small compared to 3.
The upshot of this is that Blitz is really not suitable for a calculator.
e+ means move the decimal point to the right, e- means move left.
So 1.3e+002 would mean 130 and 1.3e-004 would mean 0.00013.
As for adding 0.0000000001 and 3.0001 to get 3.0001000001, that's not going to happen.
Blitz floating point numbers are single precision, about seven digits.
That means 0.0000000001 + 3.0001 = 3.0001, the first number is simply too small compared to 3.
The upshot of this is that Blitz is really not suitable for a calculator.