Bug in Windows Calculator

Would you believe if somebody tells you that there is a bug in your window's calculator? I think you won't! You will just think how can their be a bug in windows!! That too in its calculator!! Well, you have to believe! Because there is actually a bug in it!
What is it?
Read on to know:
1. Simply open your window's calculator and insert 4 into it. .
2. Then click on the square root button to get the square root of 4. .
It will show up 2 obviously. .
3. Now subtract 2!!
What answer do you accept? 0?
That is what everyone will expect!
But its not zero!! It will show you something in decimals! So this was the bug in window's calculator! And it is said that even Microsoft Engineers do not know what is actually behind this bug?
Isn't it Amazing?
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