12
10+2
111
100+10+1
130
100+30
112
100+10+2
https://www.youtube.com/watch?v=GCcedon_N8s
look this video!
partitioning
135
100+30+5
99
90+9
123
100+20+3
137
100+30+7
https://www.youtube.com/watch?v=_8OHXbhceg8
see this video
138
100+30+8
129
100+20+9
140
100+40