python format float scientific notation

Display a decimal in scientific notation

stackoverflow.com › questions › 6913532 › display-a-decimal-in-scientific-notation

from decimal import Decimal

'%.2E' % Decimal('40800000000.00000000000000')

# returns '4.08E+10'

In your '40800000000.00000000000000' there are many more significant zeros that have the same meaning as any other digit. That's why you have to tell explicitly where you want to stop.

If you want to remove all trailing zeros automatically, you can try:

def format_e(n):
    a = '%E' % n
    return a.split('E')[0].rstrip('0').rstrip('.') + 'E' + a.split('E')[1]

format_e(Decimal('40800000000.00000000000000'))
# '4.08E+10'

format_e(Decimal('40000000000.00000000000000'))
# '4E+10'

format_e(Decimal('40812300000.00000000000000'))
# '4.08123E+10'

Answer from eumiro on Stack Overflow

Stack Overflow

stackoverflow.com › questions › 6913532 › display-a-decimal-in-scientific-notation

python - Display a decimal in scientific notation - Stack Overflow

Top answer

1 of 13

238

from decimal import Decimal

'%.2E' % Decimal('40800000000.00000000000000')

# returns '4.08E+10'

In your '40800000000.00000000000000' there are many more significant zeros that have the same meaning as any other digit. That's why you have to tell explicitly where you want to stop.

If you want to remove all trailing zeros automatically, you can try:

def format_e(n):
    a = '%E' % n
    return a.split('E')[0].rstrip('0').rstrip('.') + 'E' + a.split('E')[1]

format_e(Decimal('40800000000.00000000000000'))
# '4.08E+10'

format_e(Decimal('40000000000.00000000000000'))
# '4E+10'

format_e(Decimal('40812300000.00000000000000'))
# '4.08123E+10'

2 of 13

206

Here's an example using the format() function:

>>> "{:.2E}".format(Decimal('40800000000.00000000000000'))
'4.08E+10'

Instead of format, you can also use f-strings:

>>> f"{Decimal('40800000000.00000000000000'):.2E}"
'4.08E+10'

official documentation
original format() proposal

GeeksforGeeks

geeksforgeeks.org › python › display-scientific-notation-as-float-in-python

Display scientific notation as float in Python - GeeksforGeeks

July 23, 2025 - str.format() formats the number as a float, followed by "e+" and the appropriate power of 10. For example- 340 will be displayed as 3.4e+2 · Example: -51000000000.0000000 in scientific notation results in "5.10e+10",where the no. after "e+"denotes ...

Discussions

Best way to handle floats in scientific notation form?

You can treat them the same way you treat any other float. If by "spit them out" you mean string conversion / printing, you can format them with the 'e' option. >>> data = 6.25e+008 >>> data *= 3.14 >>> print(f"{data:.2e}") 1.96e+09 https://docs.python.org/3/library/string.html#format-specification-mini-language More on reddit.com

r/learnpython

6

1

September 3, 2022

How do I convert scientific notation number to float?

It is already a float. If you want a str with fixed decimals then you should use float formatting. One way to do this is f"{num:.20f}" More on reddit.com

r/learnpython

14

84

March 25, 2022

Is there ANY way to turn off the automatic scientific notation conversion?

Your 'very large numbers' doesn't have enough precision for you to see every digit. Use the decimal module instead. More on reddit.com

r/learnpython

7

2

December 14, 2022

How to convert scientific notation string to integer?

using an integer for scientific notation probably isn't what you want. Use a float. float('1.77e16') More on reddit.com

r/learnpython

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November 6, 2022

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