Suppose you have two 1's, two 2's and two 3's. Arrange these
six digits in a list so that:
between the two 1's there is one digit giving 1?1,
between the two 2's there are two digits giving 2??2,
and between the two 3's there are three digits giving 3???3.
Can you do the same if you only have 1's and 2's? Explain your
answer.
Can you do the same if you include two four's, and between the
two 4's there are four digits?
Here is a solution using 5's, 6's and 7's as well: