/usr/lib/x86_64-linux-gnu/libgmp.so.10 is in libgmp10 2:5.1.3+dfsg-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgmp.so.10.1.3
/usr/lib/x86_64-linux-gnu/libgmp.so.10.1.3