Arithmetic.kt

package ru.fbear.arithmetic

import kotlin.math.abs

fun main(args: Array<String>) {
    println("Hello World!")

    // Try adding program arguments at Run/Debug configuration
    println("Program arguments: ${args.joinToString()}")
}

class Arithmetic {

    /**
     * Subtracting [b] from [a]
     * @return Subtraction result.
     */
    fun subtraction(a: Int, b: Int): Int = a + negatate(b)

    /**
     * Multiply [a] by [b]
     * @return Result of multiplication.
     */
    fun multiply(a: Int, b: Int): Int {
        var sum = 0

        for (i in 1..abs(b))
            sum += a
        if (b < 0)
            sum = negatate(sum)

        return sum
    }

    /**
     * Dividing [a] by [b]
     * @return Division Result.
     */
    fun division(a: Int, b: Int): Int {
        if (b == 0) throw IllegalArgumentException("b cannot be 0")

        var dividend = abs(a)

        val divider = abs(b)

        var result = 0

        while (dividend >= divider) {
            dividend -= divider
            result++
        }

        return if ((a < 0 && b < 0) || (a > 0 && b > 0)) result
        else negatate(result)
    }

    private fun negatate(a: Int): Int {
        var num = a
        var negative = 0
        val x = if (a < 0) 1 else -1
        while (num != 0) {
            negative += x
            num += x
        }
        return negative
    }
}