Puzzles
10 December
This number is divisible by 2. One more than this number is divisible by 3. Two more than this number is divisible by 5. Three more than this number is divisible by 7. Four more than this number is divisible by 11. Five more than this number is divisible by 13.
8 December
What is the largest number of factors which a number less than a million has?
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 9 | multiple of 3 | multiple of 4 |
Today's number is the multiple of 5 formed in the first row.
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.
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):
$$
\begin{array}{ccccc}
R&A&T&S\\
N&E&R&D&+\\
\hline
S&A&N&E
\end{array}
$$Shooting hoops
Source: Alex Bolton
You spend an afternoon practising throwing a basketball through a hoop.
One hour into the afternoon, you have scored less than 75% of your shots. At the end of the afternoon, you have score more than 75% of your shots.
Is there a point in the afternoon when you had scored exactly 75% of your shots?
Rugby scores
In a rugby (union) match, 3 point are scored for a kick, 5 for a try and 7 for a converted try. This scoring system means that some total scores can be achieved in different combinations, while others can be achieved in only one way.
For example, 14 can be scored in two ways (three kicks and a try; or two converted tries), while 8 can only be achieved in one way (try and a kick).
What is the highest score which can only be made in one way?
What is the highest score which can be made in two ways?