How can I get the Nth digit of a number from right to left?

Question

How can I get the nth digit of a number when the first digit is on the right-most of the number? I'm doing this on python.

Can you post some code of what you have tried so far? Do you have some example inputs / outputs? — Cameron Downer, Aug 28 '18 at 15:58
Let's say the number is 1234.567. What is its 4th digit? Or is the number guaranteed to be an integer? — Kevin, Aug 28 '18 at 15:58
You can get the logic from [here](https://stackoverflow.com/questions/39644638/how-to-take-the-nth-digit-of-a-number-in-python) which is about nth digit from left. You can modify the same for your case. — dodobhoot, Aug 28 '18 at 16:04
Although the duplicate is asking how to count from the left rather than the right, the second answer is actually counting from the right, and the accepted one can count from either side (it’s just a matter of negative indexing), so I think your best answers are all there. — abarnert, Aug 28 '18 at 16:14

score 2 · Answer 1 · answered Aug 28 '18 at 16:00

2

You could convert the number to a string and then use a negative index to access a specific digit from the end:

>>> num = 123456
>>> n = 3
>>> str(num)[-n]
'4'

answered Aug 28 '18 at 16:00

Mureinik

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How would this deal with 123.456? should we clean out special characters? – Roy Shahaf Aug 28 '18 at 16:03
Depends on what the OP's requirement is. If you just want to skip over it you could just filter it out. – Mureinik Aug 28 '18 at 16:04

Thierry Lathuille · Answer 2 · 2018-08-28T16:09:08.293

1

If your numbers are integers, you can compute it with integer division and modulo:

def nth_digit(number, digit):
    return abs(number) // (10**(digit-1)) % 10

nth_digit(4321, 1)
# 1
nth_digit(4321, 2)
# 2

If we go further left, the digit should be 0:

nth_digit(4321, 10)
# 0

edited Aug 28 '18 at 16:09

answered Aug 28 '18 at 16:00

Thierry Lathuille

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Assuming the number is a positive (non-negative, actually) integer – Roy Shahaf Aug 28 '18 at 16:02
This provides some very odd results for negative inputs. – Patrick Haugh Aug 28 '18 at 16:02
@PatrickHaugh, RoyShahaf: That's right, I had a bit too quickly assumed I was dealing with positive integers. Corrected! – Thierry Lathuille Aug 28 '18 at 16:05

score 0 · Answer 3 · answered Aug 28 '18 at 16:04

Here's one way, assuming you are talking about integers and the decimal system:

def extract_digit(n, number):

    number = abs(number)

    for x in range(n-1):
        number = number // 10 #integer division, removes the last digit

    return number % 10

score 0 · Answer 4 · answered Aug 28 '18 at 16:13

0

Convert to a string, reverse the string, and then take the index of the string and convert the string back into an integer. This works:

def nth_digit(digit, n):
   digit = str(digit)
   return int(digit[::-1][n])

Let me know if this works for you!

answered Aug 28 '18 at 16:13

CodeRocks

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CodeRocks · Answer 5 · 2018-08-28T16:12:34.247

-2

Convert to a string, reverse the string, and then take the index of the string and convert the string back into an integer. This works:

def nth_digit(digit, n):
  digit = str(digit)
  return int(digit[::-1][n])

Let me know if this works for you!

edited Aug 28 '18 at 16:12

answered Aug 28 '18 at 16:02

CodeRocks

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If they just wanted the rightmost digit, they could just `%10`. They asked for the nth digit. – mypetlion Aug 28 '18 at 16:03

How can I get the Nth digit of a number from right to left?

5 Answers5