Puzzles
8 December
Today's number is the second smallest number that can be written as
a×b×c×d×e×f×g×h×i, where
a,b,...,i are all integers greater than 1.
7 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 25 | |||
| today's number | |||
| all digits even | |||
| multiple of 91 | multiple of 7 | cube number |
6 December
When you add up the digits of a number, the result is called the digital sum.
How many different digital sums do the numbers from 1 to 1091 have?*
* There was a mistake in this question (it previously said 1092).
If you answered the typo'd question right, your answer should automatically correct itself to 9 less than it was...
5 December
Today's number is the number of ways that 35 can be written as the sum of distinct numbers, with none of the numbers in the sum being divisible by 9.
Clarification: By "numbers", I mean (strictly) positive integers. The sum of the same numbers in a different order is counted as the same sum: eg. 1+34 and 34+1 are not different sums.
The trivial sum consisting of just the number 35 counts as a sum.
4 December
Put the digits 1 to 9 (using each digit exactly once) in the boxes so that the sums 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. Today's number is the product of the digits in the red boxes.
| + | ÷ | = 2 | |||
| + | ÷ | - | |||
| ÷ | - | = 5 | |||
| ÷ | - | × | |||
| - | × | = 4 | |||
| = 3 | = 5 | = 6 |
3 December
What is the volume of the smallest cube inside which a rectangular-based pyramid of volume 266 will fit?
2 December
What is the maximum number of lines that can be formed by the intersection
of 30 planes?
1 December
One of the digits of today's number was removed to leave a two digit number.
This two digit number was added to today's number.
The result was 619.