const overallBand = (listening: number, reading: number, writing: number, speaking: number) => {
    // overall calculating
    let calc = (listening + reading + writing + speaking) / 4;
    // getting residual
    let residual = calc - Math.trunc(calc)
    //conditional checking
    if (residual === 0) {
        return calc;
    } else if (residual >= 0.25 && residual < 0.75) {
        return `${Math.floor(calc)}.5`;
    } else if (residual <= 0.25) {
        return Math.floor(calc);
    } else if (residual >= 0.75) {
        return Math.ceil(calc);
    }
}