Extract number in every line of TSV file - bash

Question

I have a file with tab-separated-values and also with blank spaces like this:
! (desambiguación) http://es.dbpedia.org/resource/!_(desambiguación) 5
! (álbum) http://es.dbpedia.org/resource/!_(álbum_de_Trippie_Redd) 2
!! http://es.dbpedia.org/resource/!! 4
$9.99 http://es.dbpedia.org/resource/$9.99 6
Tomlinson http://es.dbpedia.org/resource/(10108)_Tomlinson 20
102 Miriam http://es.dbpedia.org/resource/(102)_Miriam 2
2003 QQ47 http://es.dbpedia.org/resource/(143649)_2003_QQ47 2
I want to extract the last number of every line:
5
2
4
6
20
2
2
For that, I have done this:
while read line;
do
NUMBER=$(echo $line | cut -f 3 -d ' ')
echo $NUMBER
done < $PAIRCOUNTS_FILE
The main problem is that some lines have more spaces than others and cut doesn't work for me with default delimiter (tab). I dont' know why, maybe because I am using WSL.
I have tried cut with several options but it doesn't work in anyway:
NUMBER=$(echo $line | cut -f 3 -d ' ')
NUMBER=$(echo $line | cut -f 4 -d ' ')
NUMBER=$(echo $line | cut -f 2)
NUMBER=$(echo $line | cut -f 3)
Hope you can help me with this. Thanks in advance.

Answer 1

I want to extract the last number of every line:
You could use grep
grep -Eo '[[:digit:]]+$' file
Or mapfile aka readarray which is a bash4+ feature.
mapfile -t array < file
printf '%s\n' "${array[#]##* }"

Answer 2

You can use awk:
awk '{print $NF}' file
With cut (if it is truly TAB separated and 3 fields per line):
cat file | cut -f3
If you have some variable number of fields per line, use rev|cut|rev to get the last field:
cat file | rev | cut -f1 | rev
Or with pure Bash and parameter expansion:
while IFS= read -r line; do
last=${line##* } # that is a literal TAB in the parameter expansion
printf "%s\n" "$last";
done <file
Or, read into a bash array and echo the last field:
while IFS=$'\t' read -r -a arr; do
echo "${arr[${#arr[#]}-1]}"
done <file
If you have a mixture of tabs and spaces you can do what usually is a mistake and break a Bash variable on white spaces in general (tabs and spaces) into an array:
while IFS= read -r line; do
arr=($line) # break on either tab or space without quotes
echo "${arr[${#arr[#]}-1]}"
done <file