OK, let's work through this together. We're starting with 581 and we're going to multiply it by 36, which means we add 581 to itself 36 times.
Step 1: 0 + 581 = 581
Step 2: 581 + 581 = 1162
Step 3: 1162 + 581 = 1743
Step 4: 1743 + 581 = 2324
Step 5: 2324 + 581 = 2905
Step 6: 2905 + 581 = 3486
Step 7: 3486 + 581 = 4067
Step 8: 4067 + 581 = 4648
Step 9: 4648 + 581 = 5229
Step 10: 5229 + 581 = 5810
Step 11: 5810 + 581 = 6391
Step 12: 6391 + 581 = 6972
Step 13: 6972 + 581 = 7553
Step 14: 7553 + 581 = 8134
Step 15: 8134 + 581 = 8715
Step 16: 8715 + 581 = 9296
Step 17: 9296 + 581 = 9877
Step 18: 9877 + 581 = 10458
Step 19: 10458 + 581 = 11039
Step 20: 11039 + 581 = 11620
Step 21: 11620 + 581 = 12201
Step 22: 12201 + 581 = 12782
Step 23: 12782 + 581 = 13363
Step 24: 13363 + 581 = 13944
Step 25: 13944 + 581 = 14525
Step 26: 14525 + 581 = 15106
Step 27: 15106 + 581 = 15687
Step 28: 15687 + 581 = 16268
Step 29: 16268 + 581 = 16849
Step 30: 16849 + 581 = 17430
Step 31: 17430 + 581 = 18011
Step 32: 18011 + 581 = 18592
Step 33: 18592 + 581 = 19173
Step 34: 19173 + 581 = 19754
Step 35: 19754 + 581 = 20335
Step 36: 20335 + 581 = 20916

So, 581*36 = 20916