How restrict a field by Min-Max value

and mall fields clear (text1.value="")

Can you clarify what you mean here? Do you want all of the 8 input fields to be cleared, or the calculated field to be cleared?

The custom calculation script could be something like:

// Custom calculation script for total fields

(function () {

    var sum = 0;

    // Array of input field names

    aFields = ["text1", "text2","text3","text4","text5","text6","text7","text8"];

    // Add up the values of the input fields

    for (var i = 0; i < aFields.length; i += 1) {

        sum += +getField(aFields[i]).value;

    }

    // Set this field value to the sum, unless it's greater than 60

    if (sum <= 60) {

        event.value = sum;

    } else {  // Clear all the fields and alert user

        event.value = "";

        resetForm(aFields);

        app.alert("Error message goes here.", 3);

    }

})();

Set the field names in the aFields array to match the names of the input fields and change the alert text.

It's your form but I think clearing the fields will make this a difficult and annoying form for your users. Consider: the user knows the rule and wants to increase field 1, then decrease field 2. But as soon as they increase field 1, all fields are cleared and they must start again. Also users often do something like this: to decrease 45 to 42, first type 2 giving 425 then remove the 5 giving 42.

Hi.

You don't need a script: select the Total field, go to Properties : Validation and enter a range of value from 0 (zero) to 60.

If you have a question about something, post it in the appropriate forum here.

Most of the trouble is caused by the calculated fields that include a numeric division operation where the denominator is zero. Whenever you do a division by a field value, you have to use JavaScript to check if the value of the denominator is zero. When you divide by zero, the result can't be formatted as a finite number, so you see the errors you're getting. This is a common problem, so you should be able to find more help with a search, but post again if you get stuck.

how to popup a custom error message? like "Total should be 1 to 60"

You need to use JavaScript, you cannot customize a built-in Acrobat message.