Brainteasers
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Brainteasers
https://www.tes.com/magazine/archive/brainteasers-87
Age 5-7
Use two + signs and two - signs.
Put them in the boxes to make the sums correct.
Minimum lines
Age 11-14
This rectangle has 9 straight lines and 14 squares. Can you find them all?
This one has 9 straight lines and 20 squares. Can you find them all?
Find the minimum number of lines needed to make a rectangle with exactly 100 squares.
BRAINTEASER SOLUTIONS
Sum fun
For example:
a. 5 - 4 + 3 + 2 - 1 = 5
b. 2 + 2 - 3 + 4 - 5 = 0
Minimum
A minimum of 15 lines are needed to form exactly 100 squares in an 8 by 5 rectangle
The total number of squares is (8 x 5) + (7 x 4) + (6 x 3) + (5 x 2) + (4 x 1) = 100
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