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I am new to Java, please help me with this: 

System.out.println(3 * (4 / 5) * 6);

Why is the answer 0?

Richard Tingle
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user3012649
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  • You could change it to a Double and get the decimal places, otherwise 4/5 = 0.8 which rounds to 0 for an Integer in Java. Try it yourself. System.out.println(4\5); – RossC Dec 17 '13 at 11:52
  • possible duplicate of [Division of integers in Java](http://stackoverflow.com/questions/7220681/division-of-integers-in-java) – Jave Dec 17 '13 at 12:36
  • In primary school you will have done integer division with remainders. 4 divided by 5 is 0 with 4 remaining. – Peter Lawrey Dec 17 '13 at 12:48

7 Answers7

8

Its a simple BODMAS Expression Evaluation

Evaluation for (3 * (4 / 5) * 6) will be;

1. (4/5)=0
2. 3*0=0
3. 0*6=0

To avoid 0 answer you can modifiy expression as 

1. (3 * (4.0 / 5.0) * 6) // return float value
2. (3*4*6)/5 //return integer value
3. (3 * (4/ 5.0) * 6)  // return float value

In these cases answer will be non-zero for this expression

Kamlesh Arya
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  • Or to remain in integer do (3*4*6)/5 - will keep as much precision as possible without having to use floats or doubles. – Tim B Dec 17 '13 at 12:02
3

(4 / 5) is 0 because they are integer values and the result of 0,8 is rounded to 0. Do (4f / 5F). Now the result will be like expected. http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html This is a usefull link for you.

kai
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0

Because you are working with Integers, not floats. 4 / 5 is 0.8, but an integer cannot store that number, so it is rounded down to 0. Then the rest of the equation is multiplying numbers by zero, which will always result in 0.

Turn the numbers into 3.0, 4.0, 5.0, 6.0 to turn the equation into a float-based one.

With integers:

3 * (4 / 5) * 6 = 0

With floats:

3.0 * (4.0 / 5.0) * 6.0 = 14.4

Mike Baxter
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0

Remember BODMAS rule

first operation will be divide means 4/5 will be evaluated and it gives 0 (because 4 and 5 are integers and it gives 0) and anything multiplied with 0 gives 0

SpringLearner
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0

The "problem" is this term:

(4 / 5)

Because both numbers are int, the result will be int. Integer arithmetic in java truncates the fractional part (it doesn't round), so the result will be zero (0.8 will become 0).

Bohemian
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0

You're using integer division (since 4 and 5 are both int):

  4 / 5 == 0 // 4/5 = 0 with remainder equals to 4: 0 * 5 + 4 == 4

that's why the whole formula

  3 * (4 / 5) * 6 == 0

If you want 4/5 treated as floating point division and so that it has a result of 0.8 you should use floating point numbers as well: 4.0 and 5.0 

  System.out.println(3 * (4.0 / 5.0) * 6); // <- 14.4

P.S. It's typical behaviour not only for Java, but for C, C++, C# as well

Dmitry Bychenko
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0

Because 4/5 = 0 in your case << It is integer division
To fix this, you can rewrite your code as follow\

System.out.println(3 * (4 / 5.0) * 6);

And the result will be

14.400000000000002
Ahmed Hamdy
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