# Different way to write Floating-Point Numbers in C++

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Different way to write Floating-Point Numbers in C++.
What is E notation in C++?
Different way to write E notation in C++.

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◕ Different way to write Floating-Point Numbers in C++

C++ has two ways to write floating-point numbers.

1st
The standard decimal-point notation which we have been using in our daily life.

Example:
21.21 is a floating-point number.

99999.22 is a floating-point number.

0.000009 is a floating-point number.

1.0 is a floating-point number.

1.0 is a floating point number. Here the fractional part is 0.
But still we have to write the decimal point which ensures that the number is represented in floating-point format and not as an integer.

2nd
We can represent floating-point values with E notation.
E notation guarantees that a number is stored in floating-point format in a program, even if no decimal point is used.
E notation is most useful for very large and very small numbers.

Example of E notation:
3.142E5

The above number means that the value 3.142 should multiplied by 100000.
The E5 means 10 to the power 5, which is 1 followed by 5 zeros.
Thus 3.142E5 means 314200.
Here 5 is called an Exponent and the 3.142 is called Mantissa.

◕ Some important examples of E notation are give bellow:

1.23e+8
We can use E or e. Both are the same meaning.
The + sigh on the exponent is optional.

1.234E-4
The exponent can be negative.
Negative exponent means to divide the number by the power of 10 instead of multiplying.
Here the result will be 1.234 / 10000.

E notation guarantees that a number is stored in floating-point format in a program, even if no decimal point is used.
6E7
This is same as 6.0E+07.

-12.34e5
We can have + or - sign in front of a floating-point number.
Here the result will be -12.34 x 100000.

E notation is most useful for very large numbers.
5.98E24
This is the mass of earth in kilograms.

E notation is most useful for very small numbers.
9.11e-31
This is the mass of an electron in kilograms.

1.2   E6
This is invalid.
Because spaces are not allowed in a floating-point number.

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