subtracting 1 digit
45-4=
41
56-10=
46
36-12=
24
56-6=
50
48-0=
48
96-2=
94
77-30=
47
18-14=
4
78-18=
60
62-30=
32
29-8=
21
81-70=
11
93-71=
22
55-55=
0
51-40=
11
47-1=
46
42-30=
12
79-58=
21
23-10=
83-0=
83
88-3=
85
55-20=
35
66-33=
33
42-22=
20
72-30=
42