In programming languages, does 0.7 + 1.4 equal to 2.1?
For most people, you probably would answer this question just like a normal math calculation. The 0.7 + 1.4 will be 2.1, just as simple as that. But wait… Let’s try it out!
Now we open the chrome browser and try it out with JavaScript developer console.
![](https://blog.jorcus.com/wp-content/uploads/2019/06/js0.7-0.14.png)
Hmm… Okay… round it up will be equal to 2.1 …
Python 3.6
![](https://blog.jorcus.com/wp-content/uploads/2019/06/python0.7-1.4.png)
It seems like python 3.6 result is same with JavaScript as well.
Michael: Okay… but it can’t say 0.7 + 1.4 is not 2.1 right?
Jorcus: Let’s check it out in the JavaScript developer console!
![](https://blog.jorcus.com/wp-content/uploads/2019/06/jstest.png)
You see that 0.7 + 1.4 is not equal to 2.1. It’s basically it has discussed a question in the past. Just like a question of “Why 0.1 + 0.2 !== 0.3?”.
This is a kind of tricky questions if you didn’t aware that the floating-point numbers can be a problem sometimes when you debug. This is because most of the programming languages can’t represent the floating-point numbers accurately. So that, if you are calculating the numbers in floating-point, you should be careful because it may not get the result as you expected.
There is a great table for all the floating decimal points in almost all programming languages! Check this out https://0.30000000000000004.com/ Also, I would recommend check a useful tools to check the exact value of a floating-point value from http://pages.cs.wisc.edu/~rkennedy/exact-float
Further readings:
Floating Point Arithmetic: Issues and Limitations
StackOverflow: Is floating point math broken?
What Every Computer Scientist Should Know About Floating-Point Arithmetic
https://0.30000000000000004.com/
WikiPedia: Floating-point arithmetic