It is used for scientific counting. Scientific counting method consists of mantissa and exponent.

"E" is the exponential part. Followed by a plus or minus sign.

"E" is mainly used to represent very large or very small numbers.

For example, 20000 can be written as 2E4 or 2E+4, which means 2 times 10 to the fourth power;

0.0005 can be written as 5E-4,

Stands for 5 times 10 to the fourth power;