1#Angular 2:the last RC version before switching to angular 4 as far as I can tell — based on this and the next version now depends on angular
2npm install @angular/cli@1.0.0-rc.2 
3ng new angular2app
4
5#Angular 4: the last CLI version before angular 5
6npm install @angular/cli@1.4.10 
7ng new angular4app
8
9#Angular 5: the last CLI version before 6
10npm install @angular/cli@1.7.4 
11ng new angular5app
12
13#Angular 6: the last CLI version before 7
14npm install @angular/cli@6.2.9 
15ng new angular6app 
16
17# Angular 7: (the last CLI version before 8
18npm install @angular/cli@7.3.9 
19ng new angular8app 
20
21#Angular 8: the last CLI version before 9
22npm install @angular/cli@8.3.25 
23ng new angular8app 
24
25#Angular 9: not last CLI version 9 
26npm install @angular/cli@9.1.12 
27ng new Angular9App

1npm install -g @angular/cli    //make sure you have node/npm installed 
2ng new <appname>        //  eg:  ng new my-app
3cd <appname>       // cd my-app
4ng serve