**QUESTION :**

Often I find myself having to drag out functions across ranges in Excel in order to find out what something will look like at a distant point. For example:

A1 = 100 B1 = 150 C1 = =(A1+B1) D1 = =(B1+C1) E1 = =(C1+D1) etc....

Or another example would be:

A1 = 100 B1 = =(A1*1.1) C1 = =(B1*1.1) D1 = =(C1*1.1) etc....

If I want to know what the 50th iteration will look like, *regardless of what this formula actually does*, is there a function I can use to calculate the nth iteration?

**ANSWER :**

This is really more of a question about mathematics than Excel specifically. Your first example looks like the Fibonacci sequence with different starting numbers, and the second is simply adding 10% to a starting figure. So after 500 iterations, your figure will be `1.1^500*100`

. There isn’t a simple formula that will extrapolate anything – you need to carefully consider what you’re doing mathematically.

Well, this might start to become a little impractical if you want the 500th iteration,

but if you’re only interested in the 50th, why not just create a series of 50 cells in Excel?

You may find it a bit more practical to use a column rather than a row,

because the rows are numbered. Taking your second example,

- Type
`100`

into cell`A1`

. - Type
`A2:A50`

into the Name Box (the thing to the left of the Formula Bar).

As you might guess, this will select cells`A2`

through`A50`

. - Type
`=A1*1.1`

, and end with`Ctrl`+`Enter`.

This will fill the selected cells with that formula.

But since you used relative addressing (`A1`

rather than`$A$1`

),

`A3`

will actually contain`A2*1.1`

,`A4`

will actually contain`A3*1.1`

, etc.

Your result will now be in cell `A50`

.

If you do decide to go for 500, and you don’t want to do all that scrolling to get to the bottom, just type `A500`

into the Name Box.