what is the missing number in this arithmetic sequence

Question

what number is missing in this arithmetic sequence 9,5,1,? -7,-11

Answer 1

The numbers in this sequence follow a common pattern.

We can find that pattern by figuring out the difference between consecutive numbers so lets start at 9.

9 - 5 = 4

As you can see to get from 9 to 5 we are subtracting 4, same with going from 5 to 1. The common difference is -4. So you can assume that the pattern is subtracting 4 from our number as we keep going, making the missing number in this sequence be -3.

We can test this since subtracting 4 from -3 will give -7, and subtracting 4 from -7 gives the last number -11.