凑十法减法

11–2﹦11–3﹦11–4﹦11–5﹦11–6﹦11–7﹦11–8﹦11–9﹦12–3﹦12–4﹦12–5﹦12–6﹦12–7﹦12–8﹦12–9﹦13–4﹦13–5﹦13–6﹦13–7﹦13–8﹦13–9﹦14–5﹦14–6﹦14–7﹦14–8﹦14–9﹦15–6﹦15–7﹦15–8﹦15–9﹦16–7﹦16–8﹦16–9﹦17–8﹦17–9﹦18–9﹦