Let's get this math done. We have 826 and we're going to multiply it by 15. This is the same as taking 826 and adding it to itself 15 times.
Step 1: 0 + 826 = 826
Step 2: 826 + 826 = 1652
Step 3: 1652 + 826 = 2478
Step 4: 2478 + 826 = 3304
Step 5: 3304 + 826 = 4130
Step 6: 4130 + 826 = 4956
Step 7: 4956 + 826 = 5782
Step 8: 5782 + 826 = 6608
Step 9: 6608 + 826 = 7434
Step 10: 7434 + 826 = 8260
Step 11: 8260 + 826 = 9086
Step 12: 9086 + 826 = 9912
Step 13: 9912 + 826 = 10738
Step 14: 10738 + 826 = 11564
Step 15: 11564 + 826 = 12390

So, 826*15 = 12390