I need more test cases for simple web forms based division calculator

Here is my approach:

The simple division of 2 integers test use cases

The WebForm contains:

TextBox1 - a TextBox2 - b TextBox3 - c Button1 - Clear Button2 - Divide

c = a / b

The test cases:

1) Check if a is valid - it can accept only integer numbers, not decimals, characters or special symbols

2) Check if b is valid - it can accept only integer numbers, not decimals, characters or special symbols

3) Check division with positive numbers

4) Check division with negative numbers

5) Check division if a = 0

6) Check division if b = 0, DivideByZeroException

7) Check division the largest possible number Int32.MaxValue by smallest possible value Int32.MinValue + 1

8) Check division if all 3 text boxes are empty

9) Check division if first (a) text boxe is empty

10) Check division if second (b) text boxe is empty

11) Check if c as a result has value with 2 decimals

12) Check division by very large positive number

13) Check division by very large negative number

14) Check division positive number by negative number

15) Check division negative number by positive number

16) Check if "Clear" deletes the content of all text boxes

Could you suggest, please, what else?