perplexus.info :: General : Binary Crossnumber Puzzle

Binary Crossnumber Puzzle - 01 (Posted on 2005-11-03)

This puzzle consists completely of binary numbers, so all the characters needed to fill in the squares will be 0s or 1s. The crossword is a 4x4 square grid, so all numbers will be written in binary, with 4 digits; e.g., 1 will be 0001, 2 will be 0010, and 4, 0100. The NOT operation changes all 0s to 1's and all 1s to 0s; e.g., NOT(0110) is 1001 and NOT(1010) is 0101.

Rows:
1. "2 Down" x 2
2. A triangular number
3. The cube of ("4 Down" - 2)
4. "3 Across" + "3 Down"

Columns:
1. NOT "2 Across"
2. NOT "1 Across"
3. "2 Across" x 2
4. "4 Across" - "1 Across"

Submitted by Erik O.

Rating: 4.0000 (3 votes)

Solution: (Hide)

The trick to solving this puzzle is the clue for 2 Across. Triangular numbers are numbers for which the number of objects can be arranged to form regular triangles. Those numbers include 1, 3, 6, 10, 15, 21, 28, ... Since we know that our binary numbers must fit within 4 bits, we are limited to the numbers 1, 3, 6, 10, and 15. The clue for 3 Down states that 2 Across must be less than 8 (otherwise "2 Across x 2" would be too large to fit in 4 bits), so we are left with 2 Across being either 1, 3, or 6. Trying them all provides us with the following solution:

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Puzzle Answer	K Sengupta	2022-03-20 01:54:54
rows - columns - down - across	tanx	2005-11-14 22:13:58
No Subject	ca	2005-11-08 21:58:29
re: a trick?	Charlie	2005-11-08 16:01:28
a trick?	frank	2005-11-08 01:21:55
Solution	Jeramie	2005-11-04 20:52:22
Way to solve	Gamer	2005-11-04 00:56:35
re: Solution	Bob Smith	2005-11-03 08:46:57
Solution	Bender	2005-11-03 07:21:44
Solution	Bender	2005-11-03 07:21:44

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