Masonry

The advertisement flyer of the contractor showed me several examples of masonry, with bricks in two colours: brown and yellow.

Which code should be substituted for the question marks?

You can look up a hint

Puzzlers are likely to value their brain power. So I’ll take this opportunity by passing on some research results: walking increases your memory

Make 21

---

1)Make 21^*
No, it’s not the card game.

The puzzle is can simply be formulated: make 21 using the numbers 1, 5, 6 and 7 once each, by combining them with the operators + – * / and the ().
The word ‘numbers’ is on purpose, i do mean numbers and not digits. And there are no tricks involved such as turning digits around, making a 9 from the 6.

Kees Krol also brought this puzzle to my attention, again: Thank you, Kees!

You can check your solution

Rowmix

One puzzle type occasionally appearing in Visie, a magazine of the Evangelical Broadcast in the Netherlands, is something the author calls “All mixed up”. I prefer “Rowmix” for reasons which will be clear once you have take a look at the puzzle rules.

Rowmix nr 1^*

	5	6	7	8
1	/2	+7	-5	x5	15
2	x4	-1	+3	/2	12
3	+8	+3	/2	-1	8
4	+7	+7	-6	-2	10
	12	8	15	22

Shuffle the numbers in every row so that a correct calculation is formed in every row and column. In doing so, all calculations are performed strictly from left to right or from top to bottom. There is no precedence of multiplication and division over addition and subtraction, and neither are there any brackets to be inserted.

For example: In the first row above you should, starting with 1, using /2, +7, -5, and x5, make 15.

Rowmix nr 2^*

	12	12	12	12
10	/2	-3	+4	+1	5
10	x2	/2	+5	-10	10
10	+10	-9	-5	-1	5
10	+14	+6	+3	+2	35
	24	12	12	12

Rowmix nr 3^*

	1	2	3	4
1	x3	/2	+8	+7	20
2	/4	+6	+2	+2	3
3	+6	+4	+3	-10	6
4	/2	+4	+3	+3	10
	20	3	8	10

You can check your solution to 1, 2, and 3

You can expect more of these puzzles in one of our e-books

Captain Brownbeard’s hourglasses

Captain Brownbeard of the pirateship “The northern star” told his first officer: “Tonight I want to sleep for 7 hours. Wake me exactly 7 hours after I leave the bridge.”

The unfortunate first officer knew that captain Brownbeard had only 1 punishment: eat so many chocolates that you never can stand the sight of chocolate again. He didnt want to suffer such a dreadful fate. To make things worse, he had only two hourglasses, one of 5 hours and one of 3 hours. How can he measure exactly 7 hours? Does he need to make any preparations in advance, and if so, which?

This puzzle is based on a puzzle with hourglasses of 4 and 7 hours which I found in both “More games for the superintelligent,” by James F. Fix and in “Denkspielereien” by Tom Werneck. The same problem can be found on numerous places on the web, with hourglasses of 7 and 11 minutes. This raises of course the question who invented this puzzle, and when?
Oh, by the way, the times used in this puzzle introduce a slight variation.

You can check your solution