How to show the result of an onclick in another div? [duplicate]

I tried every lines of code I could think of but it didn’t work. I’m stuck on these for like a week now.

    let button = document.querySelector("convert");
let celsius = document.querySelector("temp_celsius");
let fahrenheit = document.querySelector("temp_fahr");

button.onclick = function celsiusToFahrenheit(celsius){
    var fahrenheit = (9 * celsius / 5) + 32;
    return fahrenheit;
};

document.getElementById("temp_celsius").innerHTML = celsius;
document.getElementById("convert").onclick = button;
document.getElementById("temp_fahr").value;


// "temp_celsius" - id of celsius div
// "convert" - id of calculate div
// "temp_fahr" - id of fahrenheit div

/* function celsiusToFahrenheit(celsius){
    var fahrenheit = (9 * celsius / 5) + 32;
    return fahrenheit;
};  - function to convert Celsius to Fahrenheit made on exercise #2 */