A deceptively difficult piece of high school maths homework has driven a family to arguments and obsessions.
The Year 9 task set for students at Birkenhead College is based on simple addition, starting with one number written in green and added numbers through a grid to reach a final number written in red.
Easy? Not so, says mother-of-five Renee Latta.
"This is the hardest thing I've tackled in my life," she said.
• Scroll down to have a go
"Our 13-year-old son came home with this as one of the first pieces of homework for his first year in college.
"We're keen to establish good study practices for him so we were closely watching how he got on with it.
"After he sat there for a couple of hours scratching his head, my husband and I decided to help him with it.
"Pretty soon things got heated as we found out how bewildering this is."
Starting at the green number, add the numbers in a trail, horizontally or vertically, to reach the total in red.
The family took turns during the next two days trying to crack the confounding code.
At times, family members argued over wanting a turn with the work.
"It felt like I was so close to solving one of them quite a few times and then my husband would demand to take over," the full-time midwife said.
"On at least one occasion I solved one of them, only to lose track of how I'd done it so I was back to square one."
Homework advice for parents
The Ministry of Education advises helping children stuck with homework by stepping them through the exercise and explaining each stage.
The ministry-operated website parents.education.govt.nz says: "Help your child problem-solve by explaining or showing them the steps to complete a task. Let them do the steps though.
Other advice is:
* Make up a similar question or task as an example. Show them how to work through it and then get them to have a go at their homework task
* Try giving clues rather than the answer, but be aware of frustration levels - both theirs and yours
* Keep the clues simple. Remind them of all the other times they have been able to work things out
* Ideally, homework will be connected to something they've already learned, so encourage them to think back and start from what they can do.
"Don't help them too much, for example, explain where and how to find information, rather than giving it to them."
The ministry does not advise families to fight over the work.