Some multiplications can be done in an unusual
way – by moving a digit from one position to another. This challenge
is about the multiplication and... a proper number which such a
multiplication should be applied to.
Nine digits are arranged into two groups of two numbers each. When the
numbers are multiplied in each group the resulting product is the same.
What is the biggest amount which can be created in such groups?
We can arrange four 5's to produce one hundred quite easily, using some
arithmetical signs. The question is how easy it is to arrange four 7's to
obtain the same result?
This is a 3x3 square grid where the rows are the most important. Nine
different digits to be arranged into three numbers observing a special
rule. Take a look at it to see the rule...
A five-pointed star is made of circular spots held together by wire. Fill
in the circles with the correct numbers of stones from 1 through 15
observing some additional rules.
Just write a set of numbers in the circles so that any three of them lying
on a straight line always add up to the same total. Is there any algorithm
to find the proper solution?
A set of four dice, though not marked with spots in the ordinary way, but
with digits. When put together a plenty of different four-figure numbers
can be formed. How many? And what they all would add up to?
It is said that two cubes with twelve digits on their faces are enough to
produce any date of year from them. Can you discover how the digits should
be placed on the cubes?
Three cubes with three numbers on them should be arranged to create a
number divisible by 7. But is there a way to arrange the cubes in order to
get the proper number?
How many darts will you need to toss and which rings with numbers will you
need to target in order to score exactly 100? Before scoring this number
you can try to score the 50 first.
When 2 is multiplied by 2 it produces the same result as when 2 is added
to 2. It is 4 in both cases. Can you think of another pair of numbers with
the same arithmetical feature?
Digits 1 through 9 stand in a row in ascending order. Just insert a number
of pluses and minuses between them and get 100. And what about the
descending order?
