Working systematically

There are 604 NRICH Mathematical resources connected to Working systematically
Forwards Add Backwards
problem
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Forwards add backwards

Age
11 to 14
Challenge level
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What happens when you add a three digit number to its reverse?
Add to 200
problem
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Add to 200

Age
11 to 14
Challenge level
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By selecting digits for an addition grid, what targets can you make?
Cryptarithms
problem
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Cryptarithms

Age
11 to 14
Challenge level
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Can you crack these cryptarithms?
Overlaps
problem
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Overlaps

Age
11 to 14
Challenge level
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Can you find ways to put numbers in the overlaps so the rings have equal totals?
School fair necklaces
problem
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School fair necklaces

Age
5 to 11
Challenge level
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How many possible symmetrical necklaces can you find? How do you know you've found them all?
Number Daisy
problem
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Number daisy

Age
11 to 14
Challenge level
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Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?
Ribbon Squares
problem
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Ribbon squares

Age
7 to 11
Challenge level
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What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?

The Dice Train
problem
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The dice train

Age
7 to 11
Challenge level
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This dice train has been made using specific rules. How many different trains can you make?
Difference Sudoku
problem
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Difference sudoku

Age
14 to 16
Challenge level
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Use the differences to find the solution to this Sudoku.