/usr/lib/x86_64-linux-gnu/libgmp.so.10 is in libgmp10 2:6.1.0+dfsg-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.0
/usr/lib/x86_64-linux-gnu/libgmp.so.10.3.0