I have solved this issue by following below steps:
i) First connect your VPS by SSH.
ii) Then use it as the root user by using the below command from SSH.
sudo su -
iii) Now check your PHP version by using the below command from SSH.
php -v
iv) Your SSH Terminal will show the running PHP version. It will be shown like PHP 8.0.26 or any other version. Now you have to follow the below command from SSH for installing GMP.
sudo apt-get install php8.0-gmp
Hope that Now you can able to install GMP on your Ubuntu VPS.
.................. Note ..................
Example 1: If you are using PHP 8.0.26, use the below command:
sudo apt-get install php8.0-gmp
Do not use: sudo apt-get install php8.0.26-gmp
Example 2: If you are using PHP x.y.z, use the below command:
sudo apt-get install phpx.y-gmp
Do not use: sudo apt-get install phpx.y.z-gmp
