999✘37✘73
=37✘3✘111✘3✘73
=111✘111✘3✘73
=(100+11)✘(100+11)✘219
=(10000+121+1100+1100)✘219
=(12200+121)✘219
=12321✘219
=12321✘(200-1)
=12321✘200-12321
=2464200-12321
=2464200-10000-2000-300-20-1
=2454200-2000-300-20-1
=2452200-300-20-1
=2451900-20-1
=2451880-1
=2451879