The **sum()** function used to calculate sum of a numeric vector, list or data frame.

The following method shows how you can do it with syntax.

**Method 1: Use sum() Function**

```
sum(vector.na.rm=TRUE)
```

The following example shows how to use **sum()** function in R.

## Use sum() Function to Sum Values in Vector

Let’s see how we can calculate sum of values in vector:

```
# Define vector
vector1 <-c(20,25,27,29,30,32,39,40)
# Find sum of vector values
sum(vector1)
```

Output:

```
[1] 242
```

As the output shows addition of all elements of vector.

## Use sum() Function to Sum Values in Vector with Null Values

Suppose vector having null values in it then how we can calculate sum of values in vector:

```
# Define vector
vector1 <-c(20,NA,27,29,30,NA,39,NA)
# Find sum of vector values
sum(vector1,na.rm=TRUE)
```

Output:

```
[1] 145
```

The output shows the sum of all values in vector. It will avoid or remove null values while calculating sum.

## Use sum() Function to Find Sum of Values of Variable

You can use **sum()** function to calculate the sum of variable of dataframe:

```
# Create dataframe
df <- data.frame(Machine_name=c("A","B","C","D","A","A","G","B"),
Temperature=c(12,9,14,13,18,28,22,23),
Pressure=c(20,25,27,29,30,32,39,40))
# Find sum of values of Temperature column of dataframe
sum(df$Temperature)
```

Output:

```
[1] 139
```

Here the output shows sum of values of *Temperature* column of dataframe.

## Use sum() Function to Find of Sum of Values of Multiple Variables

You can apply **sum()** function on multiple variables of dataframe to calculate sum of values:

```
# Create dataframe
df <- data.frame(Machine_name=c("A","B","C","D","A","A","G","B"),
Temperature=c(12,9,14,13,18,28,22,23),
Pressure=c(20,25,27,29,30,32,39,40))
# Find sum of values of Temperature,Pressure columns of dataframe
sapply(df[ , c('Temperature', 'Pressure')], sum)
```

Output:

```
Temperature Pressure
139 242
```

The output shows sum of values for *Temperature* and *Pressure* column respectively.

Note that you can apply **sum()** function on numeric dataset to calculate sum.