notation - What is the meaning of number 1e5?

Question

I have seen in some codes that people define a variable and assign values like 1e-8 or 1e5.

for example

const int MAXN = 1e5 + 123;

What are these numbers? I couldn't find any thing on the web...

Answer 1

1e5 is a number expressed using scientific notation and it means 10 to the 5th power (the e meaning 'exponent')

so 1e5 is equal to 100000, both notations are interchangeably meaning the same.