Java doesn't know how to multiply? What? [duplicate]

Question

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Floating point arithmetic not producing exact results [duplicate] (7 answers)

Closed 9 years ago.

So I'm making a cookie clicker clone in java (shame on me) and for one thing, I need the double to increase by .1 for each cursor you own. The code looks like this (cookies is a double, and all other values are ints):

cookies = cookies + (cursors*.1+grandmas/2+farms*4+factories*10);

however, when this outputs, it outputs numbers like 2.399999999999999 instead of 2.4. What is going on?

Answer 1

That is double's precision. You could use

cookies = Math.round( cookies * 100.0 ) / 100.0;