Java Printing Wrong Answer to Arithmetic Equation

Question

System.out.println("3.14 - 5 = " + (3.14 - 5));

This statement shows 3.14 - 5 = -1.8599999999999999 in console when the answer is -1.86.

How would I be able to fix this error and what is the reason for the wrong answer being printed in the first place?

Thanks for answering my question, even though it's probably very simple :/.

Canonical http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html. — Dave Newton, Jun 05 '15 at 18:33
@DaveNewton No, but two within 10 minutes is rare, especially when they are that simmilar. — Turing85, Jun 05 '15 at 18:36
You can use rounding `System.out.printf("3.14 - 5 = %.2f%n", (3.14 - 5));` — Peter Lawrey, Jun 05 '15 at 18:40
@Turing85 Actually not so much, especially around finals time. — Dave Newton, Jun 05 '15 at 18:46

Sourav Kanta · Accepted Answer · 2015-06-05T18:37:05.563

1

When the decimal number is converted to binary it is approximated and not exact.So the subtraction is not exact.

3.14 is converted to binary ,so is 5 When the result reconverted to decimal it is not exact.Read about converting decimals to binary from this link :

edited Jun 05 '15 at 18:37

answered Jun 05 '15 at 18:35

Sourav Kanta

1 Answers1