Braille was based on a tactile military code called night writing, developed by Charles Barbier in response to Napoleon’s demand for a means for soldiers to communicate silently at night and without light. In Barbier’s system, sets of 12 embossed dots encoded 36 different sounds. It proved to be too difficult for soldiers to recognize by touch and was rejected by the military.
A similar problem can be found in L.A. Graham’s Ingenious Mathematical Problems and Methods with a range of 1 to 9, but the principle remains the same – the numbers with the smallest difference produce the largest product. You start out with the highest two digits, 7 and 6, then attach 5 and 4, putting the smaller of the two digits with the larger number, giving you 74 and 65. The next two highest digits are 3 and 2, giving you 742 and 653. Finally, you add the 1 to the lower number. Page 80 has the details of that solution.
An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower will win. The brothers, after wandering aimlessly for days, ask a wise man for advise. After hearing the advice they jump on the camels and race as fast as they can to the city. What did the wise man say?
Each son owns a camel, let’s call them Camel A and Camel B. If Camel A is slower, son A gets the fortune. If Camel B is slower, son B gets the fortune. Neither of the sons want to enter the city first because they won’t get the fortune.
When they switch camels, son A is now riding his brother’s camel (camel B) and son B is riding his brother’s camel (camel A). Now, they each want the camel they’re riding to get to the city first. If son A wins the race on camel B, that means his camel, camel A, was slower and he wins the fortune. The same is true for the other way around if the second son wins the race on camel A.
1020. There are 6 men with 2 legs each, for a total of 12 legs.
There are 36 cats with 4 legs each for a total of 144 legs.
There are 216 kittens with 4 legs each for a total of 864 legs
12 + 144 + 864 = 1020.
A word with horizontal symmetry is one whose letters are a mirror image of themselves. If you drew a horizontal line across the word and folded it over, it would overlap on itself. For example, EXCEEDED and ICEBOX have horizontal symmetry, but VERTICAL and SIMPLE do not.
What is the longest word with horizontal symmetry?