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

First, we have to install the node js to work with Typescript.

Node js providers an environment to execute the Javascript outside the browser.
Install the latest stable version of Node js. After installing node js you will have NPM (node package manager) which helps to install third-party libraries.

Open command prompt and type below command to check node js install or not
node --version
v12.16.3 (displays the version installed)

Now type the below command to install typescript
npm install -g typescript
-g this signifies that we are going to install typescript globally

After installing successfully check using below command
tsc --version
Version 3.9.2 (displays the version installed)

Now you can start working with typescript using your favorite editors like vscode, sublime Atom, etc

Have a look at the basic concepts of Typescript