Counting

There are 92 NRICH Mathematical resources connected to Counting
1 to 8
problem

1 to 8

Age
7 to 11
Challenge level
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Place the numbers 1 to 8 in the circles so that no consecutive numbers are joined by a line.
Voting Paradox
problem

Voting Paradox

Age
14 to 18
Challenge level
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Some relationships are transitive, such as `if A>B and B>C then it follows that A>C', but some are not. In a voting system, if A beats B and B beats C should we expect A to beat C?
Counting Cards
problem

Counting Cards

Age
7 to 11
Challenge level
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A magician took a suit of thirteen cards and held them in his hand face down. Every card he revealed had the same value as the one he had just finished spelling. How did this work?
Ruler
problem

Ruler

Age
16 to 18
Challenge level
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The interval 0 - 1 is marked into halves, quarters, eighths ... etc. Vertical lines are drawn at these points, heights depending on positions. What happens as this process goes on indefinitely?
Which is quicker?
problem

Which is quicker?

Age
7 to 11
Challenge level
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Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
Slippery Snail
problem

Slippery Snail

Age
7 to 16
Challenge level
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A game for two people, who take turns to move the counters. The player to remove the last counter from the board wins.
Nim-7
problem

Nim-7

Age
5 to 11
Challenge level
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Can you work out how to win this game of Nim? Does it matter if you go first or second?
Back to the Planet of Vuvv
problem

Back to the Planet of Vuvv

Age
11 to 14
Challenge level
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There are two forms of counting on Vuvv - Zios count in base 3 and Zepts count in base 7. One day four of these creatures, two Zios and two Zepts, sat on the summit of a hill to count the legs of the creatures they could see. The creature looking to the West wrote 122. The creature looking to the East wrote 22. The creature looking to the South wrote 101. The creature looking to the North wrote 41. In which direction are the 2 Zios looking and in which directions are the 2 Zepts looking?
Find a Path
problem

Find a Path

Age
5 to 7
Challenge level
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Can you find a path from a number at the top of this network to the bottom which goes through each number from 1 to 9 once and once only?
Spelling Circle
problem

Spelling Circle

Age
7 to 11
Challenge level
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Find the words hidden inside each of the circles by counting around a certain number of spaces to find each letter in turn.