Big friends

Complements to 10 for carrying or borrowing between columns.

Addition

Operation	Formula
+1	+10 -9
+2	+10 -8
+3	+10 -7
+4	+10 -6
+5	+10 -5
+6	+10 -4
+7	+10 -3
+8	+10 -2
+9	+10 -1

Subtraction

Operation	Formula
-1	-10 +9
-2	-10 +8
-3	-10 +7
-4	-10 +6
-5	-10 +5
-6	-10 +4
-7	-10 +3
-8	-10 +2
-9	-10 +1