Google Calculator Makes Mistakes

During simple subtraction Google calculator makes mistakes quite often. This doesn't happen all the time, but there is a set of digits which results in an incorrect result.

For example, 2999999999999999 minus 2999999999999998 should equal to 1, but Google calculator shows result 0. Also, when 1999999999999999 subtracting 1999999999999995 the calculator shows 0, but when 1999999999999999 minus 1999999999999993 the result is - 6 correct. And 400000000000002 minus 400000000000001 you may get a 0, but for 400000000000002 minus 400000000000000 calculator accurately gives 2.