JavaScript & Python

Details

Name Kata: Sum of Digits / Digital Root
6kuy
Description: Given n, take the sum of the digits of n. If that value has more than one digit, continue reducing in this way until a single-digit number is produced. The input will be a non-negative integer.
Example:

    16  -->  1 + 6 = 7
   942  -->  9 + 4 + 2 = 15  -->  1 + 5 = 6
132189  -->  1 + 3 + 2 + 1 + 8 + 9 = 24  -->  2 + 4 = 6
493193  -->  4 + 9 + 3 + 1 + 9 + 3 = 29  -->  2 + 9 = 11  -->  1 + 1 = 2

My Solutions

Python

def digital_root(n: int) -> int:
    n_str = str(n)
    while len(n_str) > 1:
        r = 0
        for i in range(len(n_str)):
            r = r + int(n_str[i])
        n_str = str(r)
    return n if (n >= 0 and len(str(n)) == 1) else r

JavaScript(TypeScript4)

export const digitalRoot = (n:number):number => {
    return String(n).length == 1 
      ? n : digitalRoot(
        String(n).split("").map((n) => Number(n)).reduce(
          (previousValue, currentValue) => previousValue + currentValue, 0)
      )
};

PHP

Details

Name Kata: You're a square!
7kuy
Description: You like building blocks. You especially like building blocks that are squares. And what you even like more, is to arrange them into a square of square building blocks!

However, sometimes, you can't arrange them into a square. Instead, you end up with an ordinary rectangle! Those blasted things! If you just had a way to know, whether you're currently working in vain… Wait! That's it! You just have to check if your number of building blocks is a perfect square.
Task

Given an integral number, determine if it's a square number:

In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself.

The tests will always use some integral number, so don't worry about that in dynamic typed languages.
Example:

-1  =>  false
 0  =>  true
 3  =>  false
 4  =>  true
25  =>  true
26  =>  false

My Solutions

function isSquare(int $n): bool {
  return sqrt($n) == (int)sqrt($n) ? true : false;
}

SQL

Details

Name Kata: SQL Basics: Truncating
7kuy
Description: Given the following table 'decimals':
decimals table schema

id
number1
number2

Return a table with a single column towardzero where the values are the result of number1 + number2 truncated towards zero.

My Solutions

SELECT TRUNC(number1 + number2) AS towardzero FROM decimals