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Puzzles

7 December

In September, my puzzle appeared as Alex Bellos's Monday Puzzle. The puzzle asked what the highest rugby score was which can only be made with one combination of kicks, tries and converted tries.
What is the highest rugby score which can be made with 101 different combinations of kicks, tries and converted tries?

6 December

Put the digits 1 to 9 (using each digit once) in the boxes so that the three digit numbers formed (reading left to right and top to bottom) have the desired properties written by their rows and columns.
multiple of 5
multiple of 7
cube number
multiple of 9multiple of 3multiple of 4
Today's number is the multiple of 5 formed in the first row.

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Tags: numbers, grids

5 December

How many different triangles are there with a perimeter of 100 and each side having an integer length?
(different = not rotations or reflections)

4 December

Put the digits 1 to 9 (using each digit exactly once) in the boxes so that the sums reading across and down are correct. The sums should be read left to right and top to bottom ignoring the usual order of operations. For example, 4+3×2 is 14, not 10.
-+= -4
+ + +
-÷= -1
- ÷ ×
-×= -30
=
0
=
2
=
54
The answer is the product of the digits in the red boxes.

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Tags: numbers, grids

3 December

In August, I wrote about MENACE, a machine learning robot built from matchboxes which plays noughts and crosses. How many matchboxes are needed to build MENACE?
Tags: menace

2 December

In a week (Monday 12:01 to Monday 12:01 a week later), how many times will the minute hand of an analogue clock point in the same direction as the hour hand?

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Tags: clocks, time

1 December

What is area of the largest area rectangle which will fit in a circle of radius 10?

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Santa

Each of the letters D, A, Y, S, N, T, B, R and E represents a different non-zero digit. The following sum is true:
$$ \begin{array}{cccccc} D&A&D&D&Y\\ B&E&A&R&D&+\\ \hline S&A&N&T&A \end{array} $$
This has a unique solution, but I haven't found a way to find the solution without brute force. This less insightful sum is also true with the same values of the letters (and should allow you to find the values of the letters using logic alone):
$$ \begin{array}{ccccc} R&A&T&S\\ N&E&R&D&+\\ \hline S&A&N&E \end{array} $$

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