Contents
A quick tutorial on how to round to two decimal places in Python.
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Introduction
There are many ways to round a number in Python. In this article, we’ll look at a few different ways to round a number to two decimal places in Python.
One way to round a number is to use the built-in round() function. The syntax for the round() function is:
round(number, ndigits)
where number is the number to be rounded and ndigits is the number of decimal places to round to.
For example, if we have a number like 12.3456 and we want to round it to two decimal places, we can use the following code:
rounded = round(12.3456, 2)
print(rounded) # 12.35
As you can see, the rounded variable now contains the value 12.35 (two decimal places).
What is Rounding?
When we talk about rounding, we usually mean finding the nearest whole number to a given number. For example, if we have the number 12.5 and we want to round it to the nearest whole number, we would end up with 13.
Why Round To Two Decimal Places?
Rounding is a way of displaying an approximation to a number. It is often used when estimating, or when we need to fit a lot of data into a small space.
For example, if we wanted to plot the height of every person in the United States, we would need to round to the nearest inch because there are too many people to plot every person at their exact height.
Another time when you might need to round is when you are doing currency conversions. Most currencies are only traded in two decimal places, so you will need to round to get an accurate conversion.
You can round a number in Python using the round() function. The round() function takes two arguments:
The number you want to round
The number of decimal places you want to round to
How To Round Numbers In Python?
There are a few ways to round numbers in Python. The most common is to use the built-in round() function. This function rounds a number to the nearest integer, if no decimal places are specified, or to the nearest number with the specified number of decimal places.
The syntax for round() is:
round(number, num_decimal_places)
where:
– number is the number to be rounded.
– num_decimal_places is the optional number of decimal places to rounds to. If this parameter is omitted, the number will be rounded to the nearest integer.
Rounding To Two Decimal Places In Python
Most often, when we want to round a number in Python, we use the built-in round() function. However, this function rounds to the nearest integer, which might not be what we want if we’re working with decimal values.
To round to two decimal places in Python, we can use the round() function. We simply need to specify the number of decimal places we want as an argument. For example:
“`
>>> round(1.2345, 2)
1.23
“`
Alternatively, if we want to round up or down to the nearest 10th or 100th, we can use Python’s math module. For example:
“`
>>> import math
>>> math.floor(1.2345 * 100) / 100 # rounds down to 1.23
1.23
>>> math.ceil(1.2345 * 100) / 100 # rounds up to 1.24
1.24
“`
Rounding Numbers Up or Down
If we want to round to a certain number of decimal places, we have to specify that, too. For example, if we want to round 2.665 up or down to the nearest hundreth, we have to specify how many decimal places we want: 2.665 rounded to 2 decimal places is 2.67.
To round a number up or down in Python, we use the built-in round() function. The round() function takes two arguments: the number you want to round, and the number of decimal places you want to round it to. Here are a few examples:
print(round(2.665, 2))
print(round(2.675, 2))
print(round(2.685, 2))
This would output the following:
2.67
2.68
2.69
Rounding to the Nearest Integer
The easiest way to round to the nearest integer is just to use the built in round function. All you have to do is pass in the number that you want to round and it will return the nearest integer.
In [1]: round(3.1415)
Out[1]: 3
If you want to control how Python rounds your number, you can use the rounding mode parameter. This parameter controls what Python does when it encounters a tie when rounding (for example, 1.5 rounds up to 2 but 2.5 rounds down to 2). The valid values for this parameter are “rounding up” (the default), “rounding down”, “rounding towards zero”, and “rounded away from zero”.
In [2]: import decimal
…: decimal.getcontext().rounding = decimal.ROUND_DOWN
In [3]: decimal.Decimal(‘1.5’)
Out[3]: Decimal(‘1’)
Rounding to the Nearest Ten, Hundred, etc
To round to the nearest 10, 100, 1000, etc, we can use the round() function. All we need to do is specify the number of decimal places we want Python to round to. In the following example, we round to 2 decimal places:
Rounding to an Arbitrary Number of Decimal Places
Rounding to an arbitrary number of decimal places is easy in Python 3. Just use the round(number,decimals) function. For example, to round 4.567 to three decimal places, use the code round(4.567, 3). The result is 4.567
To round 4.567 to two decimal places, use the code round(4.567, 2). The result is 4.57
You can also use negative numbers for the decimals argument. This rounds the number to the left of the decimal point. For example, to round 4.567 to the nearest tenth, use the code round(4.567, -1). The result is 4.6
Conclusion
In this article, we saw how to round a number to two decimal places in Python. We also looked at the different ways to do this and what the trade-offs are.
