Kata

Your Job

Find the sum of all multiples of n below m

Keep in Mind

• n and m are natural numbers (positive integers)
• m is excluded from the multiples

Examples

sumMul(2, 9)   ==> 2 + 4 + 6 + 8 = 20
sumMul(3, 13)  ==> 3 + 6 + 9 + 12 = 30
sumMul(4, 123) ==> 4 + 8 + 12 + ... = 1860
sumMul(4, -7)  ==> "INVALID"

Kata.SumMul(2, 9)   => 2 + 4 + 6 + 8 = 20
Kata.SumMul(3, 13)  => 3 + 6 + 9 + 12 = 30
Kata.SumMul(4, 123) => 4 + 8 + 12 + ... = 1860
Kata.SumMul(4, 1)   // throws ArgumentException
Kata.SumMul(0, 20)  // throws ArgumentException

sum_mul(2, 9)   ==> 2 + 4 + 6 + 8 = 20
sum_mul(3, 13)  ==> 3 + 6 + 9 + 12 = 30
sum_mul(4, 123) ==> 4 + 8 + 12 + ... = 1860
sum_mul(4, -7)  ==> "INVALID"

Kata.sumMul(2, 9)   ==> 2 + 4 + 6 + 8 = 20
Kata.sumMul(3, 13)  ==> 3 + 6 + 9 + 12 = 30
Kata.sumMul(4, 123) ==> 4 + 8 + 12 + ... = 1860
Kata.sumMul(4, -7)  // throws IllegalArgumentException

sumMul(2, 9)   // => 2 + 4 + 6 + 8 = Some(20)
sumMul(3, 13)  // => 3 + 6 + 9 + 12 = Some(30)
sumMul(4, 123) // => 4 + 8 + 12 + ... = Some(1860)
sumMul(4, -7)  // => None (m must be greater than 0)
sumMul(-4, 7)  // => None (n must be greater than 0)
sumMul(0, 2)   // => None
sumMul(2, 0)   // => None

      SumMul(2, 9)   => 2 + 4 + 6 + 8 = 20
      SumMul(3, 13)  => 3 + 6 + 9 + 12 = 30
      SumMul(4, 123) => 4 + 8 + 12 + ... = 1860
      SumMul(4, 1)   => -1
      SumMul(0, 20)  => -1