I have seen in some codes that peaple define a variable and assign values like 1e-8 or 1e5 for example
const int MAXN = 1e5 + 123;
what are these numbers?! I couldnt find any thing on the web...
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.
this is scientific notation for 10^5 = 100000
1e5 means 1*10^5.similarly, 1.234e5 means 1.234 * 10^5.Generally, XeY means x * 10^Y.
1e5 is 100000. 5 stand for the amount of zeros you add in behind that number. For example, lets say I have 1e7. I would put 7 zeros behind 1 so it will become 10,000,000. But lets say that the number is 1.234e6. You would still add 6 zeros at the end of the number so it's 1.234000000, but since there is that decimal, you would have to move it to the right 6 times since it's e6.
来源：https://stackoverflow.com/questions/26174531/what-is-the-meaning-of-number-1e5