public static int calculate(String input){ int lhs,rhs; //short for left-hand & right-hand side char operation; Scanner scanner = new Scanner(input); lhs = scanner.nextInt(); while(scanner.hasNext()) { operation = scanner.next().charAt(0); rhs = scanner.nextInt(); switch(operation) { case '+': lhs += rhs; break; case '-': lhs -= rhs; break; case '*': lhs *= rhs; break; case '/': lhs /= rhs; break; default: //error!! wrong operation, do something break; } System.out.println(lhs); } /*todo: your name and code goes here*/ /*You need a Scanner(or StringTokenizer) to get tokens *Then you need a loop, and switch inside that loop*/ return lhs; }