Linux sort by column number

Sample data : 

# cat flle.txt
1  field1  11
2  field2  40
3  field3  09
4  field4  22


Sort by column 3  ( lowest to highest ) - 

# cat file.txt | sort  -k3
3  field3  09
1  field1  11
4  field4  22
2  field2  40

Sort by column 3  ( highest to lowest ) - 

# cat file.txt | sort  -r -k3
2  field2  40
4  field4  22
1  field1  11
3  field3  09

Thanks