Let's roll up our sleeves and solve this. We have 549 and we're going to multiply it by 31, essentially adding 549 to itself 31 times.
Step 1: 0 + 549 = 549
Step 2: 549 + 549 = 1098
Step 3: 1098 + 549 = 1647
Step 4: 1647 + 549 = 2196
Step 5: 2196 + 549 = 2745
Step 6: 2745 + 549 = 3294
Step 7: 3294 + 549 = 3843
Step 8: 3843 + 549 = 4392
Step 9: 4392 + 549 = 4941
Step 10: 4941 + 549 = 5490
Step 11: 5490 + 549 = 6039
Step 12: 6039 + 549 = 6588
Step 13: 6588 + 549 = 7137
Step 14: 7137 + 549 = 7686
Step 15: 7686 + 549 = 8235
Step 16: 8235 + 549 = 8784
Step 17: 8784 + 549 = 9333
Step 18: 9333 + 549 = 9882
Step 19: 9882 + 549 = 10431
Step 20: 10431 + 549 = 10980
Step 21: 10980 + 549 = 11529
Step 22: 11529 + 549 = 12078
Step 23: 12078 + 549 = 12627
Step 24: 12627 + 549 = 13176
Step 25: 13176 + 549 = 13725
Step 26: 13725 + 549 = 14274
Step 27: 14274 + 549 = 14823
Step 28: 14823 + 549 = 15372
Step 29: 15372 + 549 = 15921
Step 30: 15921 + 549 = 16470
Step 31: 16470 + 549 = 17019

So, 549*31 = 17019