To install Angular CLI we need node js in the system .so download the latest stable node js.
Node provides some tools to build Angular projects. It helps to execute Javascript code outside the browser.

After installing node js we use NPM(Node Package Manager) to install third-party libraries. To install Angular CLI.

npm install -g @angular/cli

-g in the command specifies your installing the Angular CLI globally.

To check if the installation is successful.

ng --version