OK, let's work through this together. We're starting with 999 and we're going to multiply it by 67, which means we add 999 to itself 67 times.
Step 1: 0 + 999 = 999
Step 2: 999 + 999 = 1998
Step 3: 1998 + 999 = 2997
Step 4: 2997 + 999 = 3996
Step 5: 3996 + 999 = 4995
Step 6: 4995 + 999 = 5994
Step 7: 5994 + 999 = 6993
Step 8: 6993 + 999 = 7992
Step 9: 7992 + 999 = 8991
Step 10: 8991 + 999 = 9990
Step 11: 9990 + 999 = 10989
Step 12: 10989 + 999 = 11988
Step 13: 11988 + 999 = 12987
Step 14: 12987 + 999 = 13986
Step 15: 13986 + 999 = 14985
Step 16: 14985 + 999 = 15984
Step 17: 15984 + 999 = 16983
Step 18: 16983 + 999 = 17982
Step 19: 17982 + 999 = 18981
Step 20: 18981 + 999 = 19980
Step 21: 19980 + 999 = 20979
Step 22: 20979 + 999 = 21978
Step 23: 21978 + 999 = 22977
Step 24: 22977 + 999 = 23976
Step 25: 23976 + 999 = 24975
Step 26: 24975 + 999 = 25974
Step 27: 25974 + 999 = 26973
Step 28: 26973 + 999 = 27972
Step 29: 27972 + 999 = 28971
Step 30: 28971 + 999 = 29970
Step 31: 29970 + 999 = 30969
Step 32: 30969 + 999 = 31968
Step 33: 31968 + 999 = 32967
Step 34: 32967 + 999 = 33966
Step 35: 33966 + 999 = 34965
Step 36: 34965 + 999 = 35964
Step 37: 35964 + 999 = 36963
Step 38: 36963 + 999 = 37962
Step 39: 37962 + 999 = 38961
Step 40: 38961 + 999 = 39960
Step 41: 39960 + 999 = 40959
Step 42: 40959 + 999 = 41958
Step 43: 41958 + 999 = 42957
Step 44: 42957 + 999 = 43956
Step 45: 43956 + 999 = 44955
Step 46: 44955 + 999 = 45954
Step 47: 45954 + 999 = 46953
Step 48: 46953 + 999 = 47952
Step 49: 47952 + 999 = 48951
Step 50: 48951 + 999 = 49950
Step 51: 49950 + 999 = 50949
Step 52: 50949 + 999 = 51948
Step 53: 51948 + 999 = 52947
Step 54: 52947 + 999 = 53946
Step 55: 53946 + 999 = 54945
Step 56: 54945 + 999 = 55944
Step 57: 55944 + 999 = 56943
Step 58: 56943 + 999 = 57942
Step 59: 57942 + 999 = 58941
Step 60: 58941 + 999 = 59940
Step 61: 59940 + 999 = 60939
Step 62: 60939 + 999 = 61938
Step 63: 61938 + 999 = 62937
Step 64: 62937 + 999 = 63936
Step 65: 63936 + 999 = 64935
Step 66: 64935 + 999 = 65934
Step 67: 65934 + 999 = 66933

So, 999*67 = 66933