Numbers and format: What does this number mean: 1.9e-08

[Andrew Kenny]

The tabulate, summarize command gives this value of a mean: 1.9e-08

My question is very basic.

What does the e-08 signify?

Does it signify exponent or negative? Does it imply harmlessly that there are many more digits (perhaps 8) after the decimal that are not displayed?
Does it imply the number is extremely close to zero?

I have examined the "format" command and it is question still puzzles.

How can I change the format to something plain, such as show 2 decimals without the "e-08" if that is appropriate?

I have tried this:

format variable %9.2g

[Nick Cox]

See https://en.wikipedia.org/wiki/Scientific_notation

e means here power of 10. e6 would be 1 million, e-6 1 part in 1 million.

Your number is about 2 parts in 100 million

If you want that with 2 decimal places it will just show as 0.00.

Some examples with 1.92 (I don't know why I typed 1.92, but the principle is the same).

. di %9.2g 1.92e-08
  1.9e-08

. di %9.2f 1.92e-08
     0.00

. di %11.10f 1.92e-08
0.0000000192

[Ananda Hertian]

Thank you so much, Nick!