After teaching her class all about roman numerals (X = 10, IX=9 and so on) the teacher asked her class to draw a single continuous line and turn IX into 6. The only stipulation the teacher made was that the pen could not be lifted from the paper until the line was complete.
The digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 can be arranged into an addition sum to add up to almost any total, except that nobody has yet found a way to add up to 1984. However 9 digits can equal 1984 by an addition sum. Which digit is omitted?
You are given an equilateral triangle of three matchsticks like given figure. What is the minimum number of sticks needed to add three more equilateral triangles to it?
