How to take the nth digit of a number in python

You can do it with integer division and remainder methods

def get_digit(number, n):    return number // 10**n % 10get_digit(987654321, 0)# 1get_digit(987654321, 5)# 6

The // performs integer division by a power of ten to move the digit to the ones position, then the % gets the remainder after division by 10. Note that the numbering in this scheme uses zero-indexing and starts from the right side of the number.

First treat the number like a string

number = 9876543210number = str(number)

Then to get the first digit:

number[0]

The fourth digit:

number[3]

EDIT:

This will return the digit as a character, not as a number. To convert it back use:

int(number[0])

I was curious about the relative speed of the two popular approaches - casting to string and using modular arithmetic - so I profiled them and was surprised to see how close they were in terms of performance.

(My use-case was slightly different, I wanted to get all digits in the number.)

The string approach gave:

         10000002 function calls in 1.113 seconds   Ordered by: cumulative time   ncalls  tottime  percall  cumtime  percall filename:lineno(function) 10000000    1.113    0.000    1.113    0.000 sandbox.py:1(get_digits_str)        1    0.000    0.000    0.000    0.000 cProfile.py:133(__exit__)        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}

While the modular arithmetic approach gave:

         10000002 function calls in 1.102 seconds   Ordered by: cumulative time   ncalls  tottime  percall  cumtime  percall filename:lineno(function) 10000000    1.102    0.000    1.102    0.000 sandbox.py:6(get_digits_mod)        1    0.000    0.000    0.000    0.000 cProfile.py:133(__exit__)        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}

There were 10^7 tests run with a max number size less than 10^28.

Code used for reference:

def get_digits_str(num):    for n_str in str(num):        yield int(n_str)def get_digits_mod(num, radix=10):    remaining = num    yield remaining % radix    while remaining := remaining // radix:        yield remaining % radixif __name__ == '__main__':    import cProfile    import random    random_inputs = [random.randrange(0, 10000000000000000000000000000) for _ in range(10000000)]    with cProfile.Profile() as str_profiler:        for rand_num in random_inputs:            get_digits_str(rand_num)    str_profiler.print_stats(sort='cumtime')    with cProfile.Profile() as mod_profiler:        for rand_num in random_inputs:            get_digits_mod(rand_num)    mod_profiler.print_stats(sort='cumtime')