Consecutive Numbers- Mental Maths

Challenge Task:

Well I wonder how often you have noticed that there are numbers around the place that follow one after another 1, 2, 3 … etc.? Sometimes they appear in reverse order when a countdown is happening for a launch of a rocket. But usually they happen in an order going up, like when you read through a book and notice the page numbers. These kinds of numbers are called consecutive numbers, you may have heard of the word before – it simply means that they are whole numbers that follow one after another.

So this is how it starts. You need to choose any four consecutive numbers and place them in a row with a bit of a space between them, like this:

When you’ve chosen your consecutive numbers, stick with those same ones for quite a while, exploring ideas before you change them in any way. Now place + and − signs in between them, something like this :

4 + 5 – 6 + 7
4 – 5 + 6 + 7

Now work out the answers to all your calculations (e.g. 4 – 5 + 6 + 7 = 12 and so on).
Now try other sets of four consecutive numbers and look carefully at the sets of answers that you get each time.
Are you surprised by anything you notice?