I have datafram that looks like:

Data i have looks like..

```
 Tester Type    Subject Type    Time        1     2     3
 TType1         SType1          Day 1       11    2     1         
 TType1         SType2          Day 1       3     2     13
 TType1         SType1          Day 2       2     3     15
 TType2         SType3          Day 2       1     4     3
 TType3         SType3          Day 2       2     3     4
 TType1         SType1          Day 1       7     2     2
 TType2         SType1          Day 2       2     6     7

```

so the column names I have is `c(Tester.Type, Subject.Type, Time, 1, 2, 3)`

I want to create a column that calculates row means, but only when column name is numeric. 

I know how to do it straight off like:

```
avgdata <- rowMeans(data[,c(4:6)],na.rm=TRUE)

```

But is there a way to code so it automatically picks up if column names are number (`is.numeric`)?

So that way if I have more columns with numeric column names, I dont have to change column ranges?

Thank you.