Let's get this math done. We have 837 and we're going to multiply it by 45. This is the same as taking 837 and adding it to itself 45 times.
Step 1: 0 + 837 = 837
Step 2: 837 + 837 = 1674
Step 3: 1674 + 837 = 2511
Step 4: 2511 + 837 = 3348
Step 5: 3348 + 837 = 4185
Step 6: 4185 + 837 = 5022
Step 7: 5022 + 837 = 5859
Step 8: 5859 + 837 = 6696
Step 9: 6696 + 837 = 7533
Step 10: 7533 + 837 = 8370
Step 11: 8370 + 837 = 9207
Step 12: 9207 + 837 = 10044
Step 13: 10044 + 837 = 10881
Step 14: 10881 + 837 = 11718
Step 15: 11718 + 837 = 12555
Step 16: 12555 + 837 = 13392
Step 17: 13392 + 837 = 14229
Step 18: 14229 + 837 = 15066
Step 19: 15066 + 837 = 15903
Step 20: 15903 + 837 = 16740
Step 21: 16740 + 837 = 17577
Step 22: 17577 + 837 = 18414
Step 23: 18414 + 837 = 19251
Step 24: 19251 + 837 = 20088
Step 25: 20088 + 837 = 20925
Step 26: 20925 + 837 = 21762
Step 27: 21762 + 837 = 22599
Step 28: 22599 + 837 = 23436
Step 29: 23436 + 837 = 24273
Step 30: 24273 + 837 = 25110
Step 31: 25110 + 837 = 25947
Step 32: 25947 + 837 = 26784
Step 33: 26784 + 837 = 27621
Step 34: 27621 + 837 = 28458
Step 35: 28458 + 837 = 29295
Step 36: 29295 + 837 = 30132
Step 37: 30132 + 837 = 30969
Step 38: 30969 + 837 = 31806
Step 39: 31806 + 837 = 32643
Step 40: 32643 + 837 = 33480
Step 41: 33480 + 837 = 34317
Step 42: 34317 + 837 = 35154
Step 43: 35154 + 837 = 35991
Step 44: 35991 + 837 = 36828
Step 45: 36828 + 837 = 37665

So, 837*45 = 37665