Let's get this math done. We have 902 and we're going to multiply it by 40. This is the same as taking 902 and adding it to itself 40 times.
Step 1: 0 + 902 = 902
Step 2: 902 + 902 = 1804
Step 3: 1804 + 902 = 2706
Step 4: 2706 + 902 = 3608
Step 5: 3608 + 902 = 4510
Step 6: 4510 + 902 = 5412
Step 7: 5412 + 902 = 6314
Step 8: 6314 + 902 = 7216
Step 9: 7216 + 902 = 8118
Step 10: 8118 + 902 = 9020
Step 11: 9020 + 902 = 9922
Step 12: 9922 + 902 = 10824
Step 13: 10824 + 902 = 11726
Step 14: 11726 + 902 = 12628
Step 15: 12628 + 902 = 13530
Step 16: 13530 + 902 = 14432
Step 17: 14432 + 902 = 15334
Step 18: 15334 + 902 = 16236
Step 19: 16236 + 902 = 17138
Step 20: 17138 + 902 = 18040
Step 21: 18040 + 902 = 18942
Step 22: 18942 + 902 = 19844
Step 23: 19844 + 902 = 20746
Step 24: 20746 + 902 = 21648
Step 25: 21648 + 902 = 22550
Step 26: 22550 + 902 = 23452
Step 27: 23452 + 902 = 24354
Step 28: 24354 + 902 = 25256
Step 29: 25256 + 902 = 26158
Step 30: 26158 + 902 = 27060
Step 31: 27060 + 902 = 27962
Step 32: 27962 + 902 = 28864
Step 33: 28864 + 902 = 29766
Step 34: 29766 + 902 = 30668
Step 35: 30668 + 902 = 31570
Step 36: 31570 + 902 = 32472
Step 37: 32472 + 902 = 33374
Step 38: 33374 + 902 = 34276
Step 39: 34276 + 902 = 35178
Step 40: 35178 + 902 = 36080

So, 902*40 = 36080