Free games › Number Target › How a solver cracks it
How a solver cracks Number Target
Number Target gives you six numbers and a target. A solver does not guess. It searches, in a fixed order, and it is built to find the shortest route first.
The method
- Start with the six numbers. Check whether any of them already equals the target.
- Combine two. Take any two numbers in the list and apply +, −, × or ÷. Keep the result only if it is a whole, positive number. The two used numbers leave the list and the result joins it, so the list gets one shorter.
- Try one step everywhere, then two, then three. This is called iterative deepening. It means the first exact hit it finds uses the fewest possible steps.
- Skip repeats. Two different orders can leave the same list of numbers; the solver remembers lists it has seen at the same depth and does not explore them twice, and it tries a + b only once, not also b + a.
Worked example
Numbers 100, 75, 10, 9, 10, 6, target 191. The solver reaches the target in 3 steps: 100 + 75 = 175, then 10 + 6 = 16, then 175 + 16 = 191. To get there it examined about 2,965 partial answers, which is why it is quick for a computer and too many for a person.
What a person can borrow
- Work backward. Ask which pair of numbers lands near the target, instead of only building forward.
- Estimate first. Find the big multiple that gets you into the neighbourhood, then use the small numbers to close the gap.
- Fewer steps is a sign. A route with many steps usually means a shorter one exists.
- Free to play
- No sign-up to start
- Coaching built in
- Play with friends in groups