Puzzle 61
What is the next number in this sequence:
1 1 2 4 3 9 4 61 5 52 6 63 7 94 8 {?}
Puzzle Copyright © Kevin Stone
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Hint
Can you see 1, 2, 3, …?
Answer
46.
Reasoning
Take the numbers in pairs, square the first, and reverse the digits.
1 1 (1 x 1 = 1, reversed is 1)
2 4 (2 x 2 = 4, reversed is 4)
3 9 (3 x 3 = 9, reversed is 9)
4 61 (4 x 4 = 16, reversed is 61)
5 52 (5 x 5 = 25, reversed is 52)
6 63 (6 x 6 = 36, reversed is 63)
7 94 (7 x 7 = 49, reversed is 94)
so we require:
8 46 (8 x 8 = 64, reversed is 46)
Puzzle 62
Here we have a rectangular room, measuring 30 feet by 12 feet, and 12 feet high.
There is a spider in the middle of one of the end walls, 1 foot from the ceiling (A).
There is a fly in the middle of the opposite wall, 1 foot from the floor (B).
What is the shortest distance that the spider must crawl in order to reach the fly?
The Spider and the Fly – The Canterbury Puzzles, Henry Ernest Dudeney.
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Hint
Going down and across the floor isn't the only route.
Answer
40 feet.
Explanation Diagram
If you imagine the room to be a cardboard box, you can 'unfold' the room in various ways, and each route gives a different answer.

We can use Pythagoras' theorem (a2 + b2 = c2) to calculate the distances:
distance2 = horizontal2 + vertical2
distance = √(horizontal2 + vertical2)
Route #1
distance = 1 + 30 + 11 = 42 feet.
Route #2
horizontal = 6 + 30 + 6 = 42 feet.
vertical = 10 feet.
distance = √(422 + 102) ≈ 43.174 feet.
Route #3
horizontal = 1 + 30 + 6 = 37 feet.
vertical = 6 + 11 = 17 feet.
distance = √(372 + 172) ≈ 43.178 feet.
Route #4
horizontal = 1 + 30 + 1 = 32 feet.
vertical = 6 + 12 + 6 = 24 feet.
distance = √(322 + 242) = 40 feet.
Puzzle 63
What word goes in the brackets:
food [road] hard
weep [----] fall
Puzzle Copyright © Kevin Stone
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Hint
The letters come from the two words on the outside.
Answer
Leap.
From the third letter of the second word, plus the third letter of the first word, plus the second letter of the second word, plus the fourth letter of the first word.
Puzzle 64
I started a journey to my Aunt's yesterday with a full tank of gasoline, 10 gallons, but at that exact moment my gasoline tank sprang a leak.
I managed to drive 50 miles, in exactly one hour, before coming to a complete stop with an empty tank.
I know that the car manages 25 miles per gallon.
How quickly was I losing gasoline?
Puzzle Copyright © Kevin Stone
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Hint
How many gallons did the journey use?
Answer
8 gallons an hour.
Reasoning
I travelled 50 miles in one hour, at 25 miles per gallon this must have used 2 gallons.
So I must have lost the other 8 gallons through the hole.
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