Monthly Archives: August 2014

Puzzle #64: 2011 Arithmetic

Using the digits in 2011 (one 2, one 0, and two 1’s) and some basic arithmetic operations, generate the integers from 0 to 20. Usually, the operations that can be used in puzzles of this sort are the four basic ones: addition, subtraction, multiplication, and division. You may use these plus factorial and what I will call “triangular”.

n! is the product of the integers from 1 to n. e.g. 4! = 24. 0! is defined as 1. Without factorial, the 0 in 2011 would be nearly useless. It is a bad century for puzzles like this. “triangular” is is the sum of the integers from 1 to n. e.g. 4 triangular = 10.)

Submit your answer to Gene Wirchenko <genew@telus.net>. Your answer should be in the form of a proof. That means to show how your answer must be correct. The deadline is Wednesday, August 27, 2014 at noon Pacific Time. I will post the answer shortly after.

Puzzle #62 Solution: Minor Puzzles

Spoiler Inside: Solution to Puzzle SelectShow

90% Done?

“So when will you have that report finished?”

“Pretty soon. I am 90% done.”

HA!

All too often, previously-unknown factors attack and now, it is going to take longer than expected. But it seems there is a rule that you can not go backwards on your percentages even if you now know that you are only, say, 40% done.

I was bit badly on this once on a uni programming course. I had one last test to do. I fully expected the test to pass, and if it did, I would be done with the coding and could write up the assignment. I was seconds away from being done, done, done!

Unfortunately, the test failed due to a peculiarity in the PHP programming language. It took me about two hours to get back to the point that I had thought I was at.

If you have something to do, there are three realistic possibilities: 1) you have not started it yet, 2) you have started it, or 3) it is done.

90%? HA!

If you do need to track by number of things done, make sure that the things are fairly small. Spending two weeks on one thing makes for weird statistics.

Puzzle #63: Odd Currency

The People’s Glorious Republic of Heinz has an unusual currency with only two denominations: five units and seven units. You have to pay someone using this currency. Work out how to do so for each of one to ten units. (Hint: The other person can give change.)

Submit your answer to Gene Wirchenko <genew@telus.net>. Your answer should be in the form of a proof. That means to show how your answer must be correct. The deadline is Wednesday, August 20, 2014 at noon Pacific Time. I will post the answer shortly after.

Puzzle #61 Solution: Dates

Spoiler Inside: Solution to Puzzle SelectShow