Installing Mautic Composer Dependency Issue

I have always ever installed Mautic with a zip file on ubuntu servers.

After reading today about Mautic 5 I decided to go ahead and give composer a try.

I get the following error:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - bandwidth-throttle/token-bucket 2.0.0 requires ext-bcmath * -> it is missing from your system. Install or enable PHP's bcmath extension.
    - mautic/core-lib 4.2.0 requires bandwidth-throttle/token-bucket ^2.0 -> satisfiable by bandwidth-throttle/token-bucket[2.0.0].
    - Root composer.json requires mautic/core-lib 4.2.0 -> satisfiable by mautic/core-lib[4.2.0].

I have tried to install bcmath again yet this does not work. I have searched the net to try and trouble shoot it but cannot find the solution.

My distribution of ubuntu is:

Distributor ID: Ubuntu
Description: Ubuntu 21.04
Release: 21.04
Codename: hirsute

I have tried apt install php7.4-bcmath
composer require bandwidth-throttle/token-bucket

Nothing working. Any one know how I can go ahead and fix this ?