Maths

343 + 635 = 978

300 + 600 = 900                                                                    

40 + 30 = 70                                                                           

3 + 5 = 8                                                                                 

900 + 70 + 8 = 978     

First I added the 300 and the 600 hundred which equaled 900 and then I added 40 and the 70 which added up to 70 and the last one I added was 3 and 8 and it equaled 8 and altogether it equaled 978.