Suduro - A blend of Sud(oku) and (Kak)uro

Suduro -- If you already know and enjoy Sudoku and/or Kakuro, there's a website that offers a blend of the two. The grid is filled like a normal Sudoku, but there are gray squares that are filled similar to Kakuro. Sums are provided for just the gray squares in each row or column. In addition, a separate box contains the sum of just the gray squares in each 3x3 square. The extra dimension of clues should make for some fun puzzles. Give it a try.

Friday Fun - Mini-Sudoku Puzzle (nine squares!)

For all of those that are tired of having to fill in a full Sudoku grid, here's a Mini-Sudoku Puzzle. The goal is to fill the nine squares with just the digits 1 to 9. The only hints provided are the "L-block" hints at each corner. Each value tells you the sum of the five squares that make up the two adjacent edges.

Note: This is not a magic square. You cannot make any assumptions about the totals of the rows, columns or diagonals.

See how quickly you can come up with the unique solution. I'll probably post the answer next Friday. In the meantime, please don't reveal the answer so others can enjoy the puzzle too. Post comments on whether you find this puzzle easy, hard, fun or frustrating. I'd be interested in your solving techniques and times, too.

Need help solving the FoxTrot Su-Dork-U?

A week ago Sunday (10/15), the FoxTrot comic strip featured a Sudorku where the grid included various math equations (hence the Dork reference) in place of the usual starting digits.

It's pretty straightforward once you get the starting digits. For those that need some help, here are some clues:

(1/3)^-1 is the reciprocal, namely (3/1)^1 or just 3

For all the square roots, obviously only take the positive root

d/dx 3x means take the derivative. In general d/dx ax^n = nax^(n-1). So you get 1*3*x^0 or just 3

For the integral from 1 to 2, you do the reverse. x^2 becomes x^3/3. Taking this from 1 to 2 results in (2^3)/3 - (1^3)/3. That gives you 7/3. But it is multiplied by 3 to get you 7.

3! means factorial or multiplying all the numbers from 3 down to 1 (3*2*1) or 6.

The sum of k from k=1 to 3, is just 1+2+3 = 6

The log10(10) means that 10^x = 10. It's essentially the number of zeroes after the 1.

0101 is binary (base 2). This is 0*8 + 1*4 + 0*2 + 1*1 = 5

By the Pythagorean theorem a^2 + b^2 = c^2. Some common Pythagorean triples are 3-4-5 and 5-12-13

-(i^2). In complex numbers, i represents the square root of -1. So this is just -(-1) or 1.

FF-F8 is a hexidecimal equation. In hex, A-F represent 10 through 15. So FF = 15*16 + 15 and F8 = 15*16 + 8. The difference is 7.

sin(pi/2 radians) is the same as sin(90 degrees) = 1

I'll post the solution in a later post...

History of Sudoku and Killer Sudoku Variations

All of us, by now should have heard of SuDoku... if you haven't, you must have been living in a box. Or maybe it is the other way around, those of us that are hooked on SuDoku are now living in a box (in the form of a 9x9 grid).

Anyway, if you have always wondered about how this little number puzzle came about, it actually first appeared in the U.S. in the May 1979 issue of Dell Pencil Puzzles & Word Games where it was called Number Place. It is believed to be the creation of a retired architect named Howard Garns, age 74 at the time.

Several years later, in 1984 it was adopted by a puzzle group in Japan and named "Suuji Wa Dokushin Ni Kagiru" ("the numbers must be single") As it became popular, this was shortened to SuDoku (Su=number, Doku=single) and was trademarked.

Other magazines in Japan, soon copied the puzzle but went with the more generic name Nanbaapureesu (phonetically "Number Place") and often just used the English spelling. Later when it was rediscoved in the U.S. and the U.K. it was titled "SuDoku" which leads to an interesting scenario. Japanese speakers call it by its English name (Number Place) and English speakers call it by its Japanese name (SuDoku).

If you are interested in reading more of the historical details or learning about numerous sudoku variations (including Killer SuDoku a.k.a. Samunamupure or Samunanpure, Greater Than SuDoku, Samurai SuDoku, Relay SuDoku, etc.) here's a link to Ed Pegg Jr.'s article on
The History of Sudoku and Sudoku Variations.

The Daily SuDoku Puzzle

I love number puzzles like these... how about you?

The Daily SuDoku Puzzle