Search for: Login To Post Digi sum Home › Community › Questions & Answers › Mental Math Q & A › Digi sum This topic has 1 reply, 2 voices, and was last updated 5 years, 1 month ago by Ofpad. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts July 12, 2018 at 7:03 am #5043 AnonymousInactive Topics: 1Replies: 0 how to use this logic for subtraction (12-54) July 12, 2018 at 7:04 am #5045 OfpadParticipant Topics: 0Replies: 158 The process is the same covered in the lecture. 12 – 54 = -42 Digit Sum 3 – 9 = -6 Author Posts Viewing 2 posts - 1 through 2 (of 2 total) You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Continue with GoogleContinue with FacebookContinue with Twitter Log In