Average of Evenly Spaced Numbers
Average a sequence without adding every term.
Average = (first + last) / 2
1How it works
For numbers in an arithmetic sequence (consecutive integers, even numbers, etc.), the average is simply the mean of the first and last terms.
2How to apply (in seconds)
- Identify the first and last numbers.
- Add them and divide by 2.
3Worked examples
Example 1 Worked solution
Q. Find the average of 11, 12, 13, …, 20.
- First = 11, last = 20.
- (11 + 20) / 2 = 31 / 2.
✓ 15.5
4When to use it
- ✦Average MCQs with long, evenly spaced lists.
5Cautions & tips
- !Works only when the numbers are equally spaced.