Hint
How many 1 x 1 squares are there, how many 2 x 2, …?
Answer
2,870 squares.
Reasoning
We have squares sizes from 1 x 1 up to 20 x 20, and these are the counts:
1 x 1 = 400
2 x 2 = 361
3 x 3 = 324
4 x 4 = 289
5 x 5 = 256
6 x 6 = 225
7 x 7 = 196
8 x 8 = 169
9 x 9 = 144
10 x 10 = 121
11 x 11 = 100
12 x 12 = 81
13 x 13 = 64
14 x 14 = 49
15 x 15 = 36
16 x 16 = 25
17 x 17 = 16
18 x 18 = 9
19 x 19 = 4
20 x 20 = 1
The legendary BrainBashers calendar had a recent bug. Here is a listing showing the number of days in each month:
January 107
February 68
March 135
April 15
May 133
June 104
July 104
August 16
September ?
Take the first letter of the month, and find its position in the alphabet: S = 19.
Then take the number of letters in the month: September = 9.
January 10-7
February 6-8
March 13-5
April 1-5
May 13-3
June 10-4
July 10-4
August 1-6
September 19-9
?
Puzzle 11
Using a 3 gallon container and a 7 gallon container (along with a water source and drain) …
… can you measure exactly 5 gallons in the fewest steps?
Answer
Here are the contents of the containers after each stage:
A B
0 7 fill B
3 4 fill A from B
0 4 empty A
3 1 fill A from B
0 1 empty A
1 0 fill A from B
1 7 fill B
3 5 fill A from B
This leaves 5 gallons in container B after 8 steps.
?
Puzzle 12
Which of the shapes is identical to the first one?
Hint
Try to rotate them around in your head, but watch out for mirror images.
Answer
A, D, and E.
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