The challenge is to hit 9000 dead-on.
I was surprised. My nephew is in Year 8 and punches above his weight in maths. I have seen him rattle off multi-digit addition problems with maddening accuracy. Why had the solution eluded him?
I scribbled away, beginning with trial and error before turning my focus to the Ones column. That already narrows the choices, because the four digits in this column must add up to 10. Regardless of how I rearrange the four numbers, the final digits must comprise 4,4,1,1 or 3,3,3,1 or 4,3,2,1. I continued down this path, hoping to systematically arrive at the solution. It was exhausting work and I could see why my nephew was struggling — there is no obvious combination that works, and there are a lot of possibilities to burn through.