regex to look for numbers or small letter alphabets of length 46 and append 0 at the end.
C:\Users\svuppula>echo "0020000000000000100000000000000000000000000001" | sed -e 's/[0-9a-z]{45}/\10/g'
sed: -e expression #1, char 20: invalid reference \1 on `s' command's RHS
where as grep works
C:\Users\svuppula>echo "0020000000000000100000000000000000000000000001" | grep -E '[0-9a-z]{45}'
"0020000000000000100000000000000000000000000001"
versions:
C:\Users\svuppula>sed --version
sed (GNU sed) 4.2.2
C:\Users\svuppula>grep --version
grep (GNU grep) 2.24
sed -r
or escape the parentheses\{
\}
and enclose the match in\([0-9a-z]\{10\}\)
in case ofsed -e