A 1 metre cube has one face on the ground and one face against a
wall. A 4 metre ladder leans against the wall and just touches the
cube. How high is the top of the ladder above the ground?
Four rods are hinged at their ends to form a convex quadrilateral.
Investigate the different shapes that the quadrilateral can take.
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Divisible Palindrome
Age 14 to 16 Short Challenge Level
Answer: 5775
Multiple of 15 $\Rightarrow$ multiple of 5 so ends in 5 or 0
0 __ __ 0 not 4 digits
5 __ __ 5
5 + __ + __ + 5 a multiple of 3
Largest possible
5 + 9 + 9 + 5 = 28 no
5 + 8 + 8 + 5 = 26 no
5 + 7 + 7 + 5 = 24 yes