Sum of All Fears: The Code

                            $("#submit").on("click", function () {

                                //Step 1: Get user data
                                let k = parseInt($("#numInK").val());
                                let num1 = parseInt($("#numIn1").val());
                                let num2 = parseInt($("#numIn2").val());
                                let num3 = parseInt($("#numIn3").val());
                                let num4 = parseInt($("#numIn4").val());
                                let num5 = parseInt($("#numIn5").val());

                                //Step 2: Create an array and add user data to it
                                let array = new Array();
                                array.push(num1);
                                array.push(num2);
                                array.push(num3);
                                array.push(num4);
                                array.push(num5);

                                //Step 3:  Perform algorithm
                                let message = "";

                                for (let i = 0; i < array.length - 1; i++) {
                                //if the number in the array is larger than k, go on to the next
                                if (array[i] > k) continue;

                                //calculate the difference between k and the next number in the array
                                let solution = k - array[i];

                                //forward search the array, beginning at the NEXT legitimate index position
                                //(index begins at position 0, so all legitimate index positions will be positive numbers.)
                                if (array.indexOf(solution, i + 1) > -1) {
                                message = `The given set of numbers DOES include a solution for a K value of ${k}.`;
                                break;
                                } else {
                                message = `The given set of numbers does NOT include a solution for a K value of ${k}.`;
                                }
                                }

                                // Step 4: Display result & clear all on click
                                $("#clear").on("click", function () {
                                $("#numInK").val("");
                                $("#numIn1").val("");
                                $("#numIn2").val("");
                                $("#numIn3").val("");
                                $("#numIn4").val("");
                                $("#numIn5").val("");
                                $("#resultOut").text("");
                                })
                                $(".numOnly").keydown(function (event) {
                                let valid = false;
                                // Allow backspace, tab, and delete
                                if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9) {
                                // let it happen
                                valid = true;
                                }
                                else {
                                // Ensure that it is a number and stop the keypress
                                if (event.keyCode >= 96 && event.keyCode <= 105) {
                                valid = true;
                                }
                                }
                                });

                                $("#resultOut").text(message);
                                });