Halfway Between 9 and 21

When you ask "What number is halfway between 9 and 21?" we assume you mean the number in the exact middle of the two numbers on a number line, as illustrated below, where X=9 and Y=21.

Halfway Between Line

To find the number halfway between 9 and 21, we use the following formula:

(X + Y)/2 = Halfway Between

When we enter 9 and 21 into our formula, we get:

(9 + 21)/2 = 15

Thus, the number halfway between 9 and 21 is 15.

To check that our answer is correct, we subtract 9 from 15 and subtract 15 from 21 and compare the two numbers:

15 - 9 = 6
21 - 15 = 6

As you can see, the halfway number is 6 higher than 9 and 6 lower than 21. Therefore, our halfway between answer of 15 above is correct.

Halfway Between
Find halfway between two other numbers here!

Halfway Between 9 and 22
Here is our next Halfway Between calculation.