# CAT 2015: On Screen Calculator could slow you down!

The CAT 2015 has announced the addition of on screen Calculator to its Online test interface this year. Based on earlier attempts to add a calculator, we expect the interface to look like the image shown below:

The important thing to remember is that the Calculator can only be used with the help of a mouse.

The keys that are likely to be available in this calculator are:

1. BS : This is the Backspace key. Use this to remove the most recent character entered.

2. CE : Clear Entry.

3. CA : Clear All.

4. Other buttons include digits from 0 to 9, decimal point, addition, subtraction, division, multiplication and an ‘=’ (equal to) button.

Difference between CE and CA:

Lets say you want to multiply 2015 and 451980

You enter 2015 correctly and then hit the multiplication button. Now after entering the 2nd number, you notice you have made multiple mistakes. You could use the ‘BS’ button and clear the characters one by one, or use the CE to “clear the current entry”. Note that, the ‘2015’ followed by the multiplication button are not cleared by using the CE button. Only the most recent entry is cleared.

If instead of CE, you use CA, the calculator will also remove ‘2015’ followed by the multiplication button from its memory. This is as good as a state of the calculator at the beginning.

How to use Calculator to compute:

Lets say you want to calculate (45.3 + 24.6)/3.8

First you calculate by entering ‘4’,’5′,’.’,’3′. You then click the ‘+’ (addition) button and enter ‘2’,’4′,’.’,’6′. Now you click on the ‘=’ button. The value of the addition shows up. After this, you click on the ‘/'(division) button and enter ‘3’,’.’,’8′ to arrive at the value.

If you notice, to compute a value as the one above, we need to click using the mouse multiple times by moving the cursor to the corresponding buttons. A calculation as simple as the one above took us an average of 14s over 5 tries.

If one were to instead approximate the above value, 45.3 + 24.6 = 69.9 ~= 70, 3.8 ~= 4. So this value is likely to very close to 18. (The correct value is 18.39).

So, dont feel a false sense of security that having the calculator will make your calculations faster. In fact, it might even slow you down if you want to verify your computation by trying it again.