How to use the Python Round method – with examples

What is the Python round method?
Basic use of the Python Round method
Using decimals with Python Round method
Example 2
Example 3
Summary
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What is the Python round method?

Round is an inbuilt Python function that returns floating-point numbers rounded to a specified number of decimal places.

The Python round function takes two arguments, the first argument is the number that is going to be rounded off while the second argument is the decimal places that we want the number rounded off to.

Basic use of the Python Round method

However, it is not mandatory that we supply two arguments to the Python round function. It is important that we note that if we supply the number as the only argument we will get the nearest number whole integer.

In the case above we are getting 15 because 15 is the nearest whole integer. Suppose that we change the number to 15.6, then in this case we are going to get 16.

Therefore, no matter how many numbers we put at the end of the float integer, if we do not supply the second argument into the Python round function it is always going to return the nearest whole integer. As illustrated in the code below.

Using decimals with Python Round method

So in order to supply the second parameter, we’ve got to put a comma just after the number that we are rounding off and then supply the second argument which is the number of decimal places that we want the number rounded off to.

We can start off by rounding off the above number to two decimal places by supplying two as the second argument.

It is important to note that this does not return the number that we are expecting. Therefore if we change the number that we are rounding off to 2.675 we would expect that we should get 2.8.

Example 2

However, in this specific instance, we get 2.7 as the result. This is because most decimal fractions can’t actually be represented as floating-point numbers.

We should note that we are using the word around and not round up or round down. This is because there is no option of either specifically rounding up or rounding down; we’re only able to round off to the nearest value.

Example 3

However, in cases where a number is equidistant, the Python round function prefers to return the nearest even number.

This can be illustrated in cases such as when we try to round off 0.5 and -0.5. In both of these cases, we get Zero since this is the closest even number.

If we also try to round off -0.5 we are also going to get 0 since this is the closest even number as well.

Summary

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