Puzzles
14 December
There are 204 squares (of any size) in an 8×8 grid of squares. Today's number is the number of squares in a 13×13 grid of squares
13 December
A book has 754 pages (numbered 1 to 754: page 1 is on the left of the first double page spread, and page 754 is on the right of the final double page spread). What do the page numbers of the middle two-page spread add up to?
12 December
Put the digits 1 to 9 (using each digit exactly once) in the boxes so that the sums are correct. Today's number is the product of the numbers in the red boxes.
| + | + | = 17 | |||
| + | + | + | |||
| + | + | = 7 | |||
| + | + | + | |||
| + | + | = 21 | |||
| = 11 | = 20 | = 14 |
11 December
Two more than today's number is the reverse of two times today's number.
10 December
How many zeros does 1000! (ie 1000 × 999 × 998 × ... × 1) end with?
9 December
Write the numbers 1 to 15 in a row. Underneath, write the same list without the first and last numbers. Continue this until you have just one number left.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | ||
| 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | ||||
| etc. | ||||||||||||||
Today's number is the sum of all the numbers you have written.
8 December
The odd numbers are written in a pyramid.
| 1 | ||||
| 3 | 5 | |||
| 7 | 9 | 11 | ||
| etc. | ||||
What is the mean of the numbers in the 23rd row?
7 December
The odd numbers are written in a pyramid.
| 1 | ||||
| 3 | 5 | |||
| 7 | 9 | 11 | ||
| etc. | ||||
What is the sum of the numbers in the seventh row?