With these types of patterns, there are actually two patterns that intertwine. A sequence for the numbers in the odd positions (Number 1, 3, 5 etc) and a sequence for the numbers in the even positions (Number 2, 4, 6 etc)). If you go through the numbers chronologically, the series does not seem to make sense. This is because the series are independent of each other. An example:
If you look at the first 3 numbers, you might see an easy pattern. However, this will put you on the wrong track. The arches look like this:
There are many different variations on this pattern. This kind of series often contains more than 4 or even 5 numbers in the problem, otherwise it is too difficult to recognize the pattern.
We will first work out 3 examples and show you how to draw the arches. Then you can do 3 practice exercises yourself.