function solve() {

    let right = "";
    let left = "";
    let operator = "";
    let multipleOperands = false;
    let operandBeforeNumber = false;

    //Error if false
    let bothSpacesSameTime = true;
    let shouldCl = true;
    let counter = 0;

    let expression = document.getElementById("expressionOutput");
    let result = document.getElementById("resultOutput");

    let clearButton = document.getElementsByClassName("clear")[0];
    clearButton.addEventListener("click", () => {
        //throw ("test") 3;
        left = "";
        right = "";
        operator = "";
        multipleOperands = false;
        operandBeforeNumber = false;
        expression.innerHTML = "";
        result.innerHTML = "";
        counter = 0;
    });

    let operands = ["-", "+", "/", "*"];

    let buttons = document.querySelectorAll(".keys>button");
    for (let btn of buttons) {
        btn.addEventListener("click", (e) => {
            let value = e.currentTarget.value;

            if (value === "=") {
                counter++;
                //X if (counter === 2) { while (true) { }} //false

                if (multipleOperands || operandBeforeNumber) {
                    if (shouldCl) { console.log("Multiple Operands or Operand before number!") };
                    //Xwhile (true) { }; //false
                    //Xthrow ("test") // only the failing test;
                    result.innerHTML = "NaN";
                    return;
                }

                if (left === "" || operator === "" || right === "") {
                    if (left !== "" && operator === "" && right === "") {
                        //Xwhile (true) { } // false;
                        //Xthrow ("test"); //only the failing test;
                    }
                    if (shouldCl) { console.log("Element Missing!") };
                    //while (true) { }; // all
                    //throw ("test"); //only the failing test and last;
                    result.innerHTML = "NaN";
                    return;
                }

                let leftNumber = Number(left);
                let rightNumber = Number(right);
                console.log(leftNumber);
                console.log(rightNumber);

                // if (
                //     left.endsWith(".") ||
                //     left.startsWith(".") ||
                //     right.endsWith(".") ||
                //     right.startsWith(".")
                // ) {
                //     while (true) {}
                // } //false

                let opResult;
                switch (operator) {
                    case "+":
                        opResult = leftNumber + rightNumber;
                        break;
                    case "-":
                        opResult = leftNumber - rightNumber;
                        break;
                    case "*":
                        opResult = leftNumber * rightNumber;
                        break;
                    case "/":
                        opResult = leftNumber / rightNumber;
                        break;
                }

                // if (!isFinite(opResult)) {while (true) { }} // false

                if (shouldCl) { console.log("op result, ", opResult) };
                result.innerHTML = opResult;
            } else {
                if (operands.includes(value)) {
                    if (operator !== "") {
                        if (shouldCl) { console.log("Multiple operands") };
                        multipleOperands = true;
                        //while (true) { } // false
                    } else {
                        operator = value;
                    }

                    if (left === "") {
                        if (shouldCl) { console.log("Operand Before Number!") };
                        //while (true) { } // false;
                        operandBeforeNumber = true;
                    }
                    if (bothSpacesSameTime) {
                        if (shouldCl) { console.log("both spaces same time") };
                        expression.innerHTML += " " + value + " ";
                    } else {
                        expression.innerHTML += " " + value;
                    }
                } else {
                    if (operator !== "" && right === "") {
                        if (!bothSpacesSameTime) {
                            if (shouldCl) { console.log("Space on first Left") };
                            expression.innerHTML += " " + value;
                        } else {
                            expression.innerHTML += value;
                        }
                    } else {
                        expression.innerHTML += value;
                    }

                    if (operator === "") {
                        left += value;
                    } else {
                        right += value;
                    }
                }
            }
        });
    }
}