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# Brainteasers

Puzzles to test mathematical skills

AGE 6-8: Six coins

Julie has six coins.

They are all pound;1 coins, 10p coins or 1p coins.

1. Exactly two of Julie's coins are pound;1 coins.

How much does she have altogether?

There are 5 possibilities. Can you find them?

2. Julie has at least one pound;1 coin, at least one 10p coin, and at least one 1p coin.

How much does Julie have altogether?

There are 10 possibilities. Can you find them?

AGE 9-11: All square

These counters form a square. So do these.

Wat is the greatest number of counters you can put on a 4x4 grid without forming a square?

* ANSWERS page 37 - Brainteaser solutions

All square

On a 2x2 grid you can fit 3 counters,

on a 3x3 grid you can fit 6 counters,

on a 4x4 grid you can fit 10 counters...

without forming a square. For example,

Six coins

1. The five possibilities are:

pound;2.04, pound;2.13, pound;2.22, pound;2.31, pound;2.40

2. The 10 possibilities are:

pound;4.11, pound;3.21, pound;3.12, pound;2.31, pound;2.22

pound;2.13, pound;1.41, pound;1.32, pound;1.23, pound;1.14

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