How to get more coins in MathMaster app?

here is massmaster app so how coins in this app so if you tap on coins you see you need to upgrade and then you will get access to 90 expert Solutions but actually if you just invite friend you can get five free Solutions so just tap get free Solutions and then you can use this code after inviting a friend after your friend downloads the app you'll boss get five free coins and you can invite one friend only and this is then your invitation code which you can use and then yeah that's what it is so and then you can if you see this video you can just enter this invitation code if nobody else enter it already and then you can just get some five free coins which every coin is once resolution so that's what you can do uh yeah unfortunately there is a cap so I can only invite one friend because I didn't do it the way that you can just instantly like invite like hundreds of friends and just have free access to the app now you can only invite one friend and that's the way to try it out this app