e-notation scientific notation

Solution 1:

Used like this, eN (much more often EN) is just a symbol for $10^N$. It is used because scientific notation is convenient for large and small numbers and it avoids the need for superscripts. Superscripts used to be much more difficult to produce than they are today, and even today they are not easy in (some) word processors.

12.5e says allocate 12 spaces to the total output (including signs, e, etc.) and put 5 behind the decimal point. In your example there is room for a leading + sign (omitted) and eleven more characters. If the format were 12.3e you would probably get 123.451e+02 You need at least seven more total characters than decimals for the leading sign, the decimal point, e, the exponent sign, and two digits of exponent.

In your example, the decimal point moves by 4 places so there are the correct number of digits before it, then the e value was chosen to give the value 4

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