Let's roll up our sleeves and solve this. We have 990 and we're going to multiply it by 36, essentially adding 990 to itself 36 times.
Step 1: 0 + 990 = 990
Step 2: 990 + 990 = 1980
Step 3: 1980 + 990 = 2970
Step 4: 2970 + 990 = 3960
Step 5: 3960 + 990 = 4950
Step 6: 4950 + 990 = 5940
Step 7: 5940 + 990 = 6930
Step 8: 6930 + 990 = 7920
Step 9: 7920 + 990 = 8910
Step 10: 8910 + 990 = 9900
Step 11: 9900 + 990 = 10890
Step 12: 10890 + 990 = 11880
Step 13: 11880 + 990 = 12870
Step 14: 12870 + 990 = 13860
Step 15: 13860 + 990 = 14850
Step 16: 14850 + 990 = 15840
Step 17: 15840 + 990 = 16830
Step 18: 16830 + 990 = 17820
Step 19: 17820 + 990 = 18810
Step 20: 18810 + 990 = 19800
Step 21: 19800 + 990 = 20790
Step 22: 20790 + 990 = 21780
Step 23: 21780 + 990 = 22770
Step 24: 22770 + 990 = 23760
Step 25: 23760 + 990 = 24750
Step 26: 24750 + 990 = 25740
Step 27: 25740 + 990 = 26730
Step 28: 26730 + 990 = 27720
Step 29: 27720 + 990 = 28710
Step 30: 28710 + 990 = 29700
Step 31: 29700 + 990 = 30690
Step 32: 30690 + 990 = 31680
Step 33: 31680 + 990 = 32670
Step 34: 32670 + 990 = 33660
Step 35: 33660 + 990 = 34650
Step 36: 34650 + 990 = 35640

So, 990*36 = 35640