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Brainteasers

Age 5-7

Line it up

Take these five cards:

Rearrange them in a row so that:

* the second card and the third card have a sum of 8;

* the third card and the fourth card have a sum of 6;

* the fourth card and the fifth card have a sum of 5.

Age 9-13

Count the rectangles

How many rectangles can you see in the diagram? (Hint: remember that a square is also a rectangle.)

What about in this diagram?

Brainteaser solutions

from page 30

Line it up

The order of cards is 2, 3, 5, 1, 4

Age old problems

There are 36 rectangles in a 3 x 3 grid of squares.

Squares:

nine 1 x 1; four 2 x 2;

one 3 x 3

Oblongs:

six 1 x 2; three 1 x 3;two 2 x 3; six 2 x 1;three 3 x 1; two 3 x 2

In a 4 x 4 grid there are 100 rectangles

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