Monthly Archives: March 2020

Bongard letters (1)

In 1967 the Russian scientist M.M. Bongard published a book containing 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conforms to a certain rule. Each box on the right contradicts this rule. Your task, of course, is to figure out the rule.

1)Bongard problem letters 1*/*****

2)Bongard problem letters 2**/*****

Though I’m in the midst of a series Bongard problems on Dates and times, I throw in a couple on letters just for a change.

New puzzles are published at least once a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars. You can check your solutions here and here

Happy puzzling!

Five five’s

Some of you may know the problem to make all the numbers from 1 to 20 with four fours.
I wrote about it here. It may come as a surprise to you that it is possible to make all the numbers from 0 to 100.

Today’s problem is to make all numbers from 0 to 20 using exactly five fives. For example:
(5*5 – 5*5) / 5 = 0

You can find my solutions here.