Solution written in Go for challenge 2012-03-23 on ProgrammingPraxis.com

challenge-2012-03-23.go

// Exercise from: http://programmingpraxis.com/2012/03/23/base-26-arithmetic/
// Exercise: Write a function that takes two base-26 numbers in which digits are represented by letters with A=0, B=1, … Z=25 and returns their product using the same notation. As an example, CSGHJ × CBA = FNEUZJA.

package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Println("base26Multiply('CSGHJ', 'CBA'):", base26Multiply("CSGHJ", "CBA"))
}

func base26Multiply(a, b string) string {
	return base10ToBase26(base26ToBase10(a) * base26ToBase10(b))
}

func base26ToBase10(a string) (number int) {
	for index, value := range a {
		number += int(float64(value-65) * math.Pow(26, float64(len(a)-index-1)))
	}

	return
}

func base10ToBase26(number int) (converted string) {
	for number > 0 {
		remainder := number % 26
		converted = string(remainder+65) + converted
		number = (number - remainder) / 26
	}

	return
}

Console output:

$ go run challenge-2012-03-23.go
base26Multiply('CSGHJ', 'CBA'): FNEUZJA