If you're baffled then you are probably not one of the brightest nine-year-old mathematicians in the country.
This is just one of 83 maths puzzles that are be sent to primary schools from next month by the Department for Education and Employment as part of a new drive to stretch gifted pupils. Other puzzles include asking children as young as five to calculate how many ways they can buy a 45p monster using only silver coins.
Ministers want teachers to identify gifted children as early as possible. They will even be asked to help select pupils to take GCSE maths while still at primary school under a new fast-track initiative being piloted this year.
Teachers will also help decide which pupils enter the new "world-class tests" for gifted children in urban areas which start in September 2001. Pupils aged nine and 13 will tackle the tests in maths and problem-solving pitched at the brightest 10 per cent. The tests will iclude puzzles and tests of lateral thinking similar to the ones in the new packs.
The pack, Mathematical challenges for able pupils in key stages 1 and 2, also gives teachers advice on how to teach gifted children. Children as young as five should be identified as mathematically gifted and given special tuition, it says. Teachers should spend the same time with each pupil but should go further in each topic with the brightest.
And, according to DFEE guidance accompanying the pack, the best mathematicians should be set harder homework and be considered for promotion to the year above. Setting by ability across year groups should also be considered. The guidance says: "Mathematically able pupils are in every school and among all ethnic and socio-economic groups.
"You can stretch them through differentiated group work, harder homework and extra challenges which they can do ... when other pupils are doing consolidation exercises."
*Answer: three Zids and four Zods
The puzzles are also on the web at www.standards.dfee.gov.uknumeracy