Sure thing, let's get straight to it. We start with 909 and we're going to multiply it by 20, which means adding 909 to itself 20 times.
Step 1: 0 + 909 = 909
Step 2: 909 + 909 = 1818
Step 3: 1818 + 909 = 2727
Step 4: 2727 + 909 = 3636
Step 5: 3636 + 909 = 4545
Step 6: 4545 + 909 = 5454
Step 7: 5454 + 909 = 6363
Step 8: 6363 + 909 = 7272
Step 9: 7272 + 909 = 8181
Step 10: 8181 + 909 = 9090
Step 11: 9090 + 909 = 9999
Step 12: 9999 + 909 = 10908
Step 13: 10908 + 909 = 11817
Step 14: 11817 + 909 = 12726
Step 15: 12726 + 909 = 13635
Step 16: 13635 + 909 = 14544
Step 17: 14544 + 909 = 15453
Step 18: 15453 + 909 = 16362
Step 19: 16362 + 909 = 17271
Step 20: 17271 + 909 = 18180

So, 909*20 = 18180