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'Carrying Cards' printed from http://nrich.maths.org/
These sixteen children are standing in four lines of four, one
behind the other. They are each holding a card with a number on
Each child in blue is holding a number which is four more than
the child in the same row wearing red.
The children in yellow shirts each have a number which is
double the number of the child in the same row wearing red.
Some of the numbers that the children in red, blue or yellow
shirts are holding have got rubbed off. What should the numbers
Can you work out how the numbers that the children in green
are holding have been worked out? What are the two missing
If there was another row of four children standing behind the
fourth row, what numbers would they be holding?