# Excel/excel formula

Question
Dear Sir,

Using Excel for MAC 2011 V14. Level 3?

I would like to calculate how many years and months a certain amount of money will last given the following:

\$100,000 at 1.5%per annum, no monthly deposits, and \$3000 per month withdrawn.

It would be handy to have 3 cells to enter these amounts so that they may be changed to different values, and one cell returning the time period calculated.

Thank you,

Dennis Smith

Hi Dennis,

It would take 35 months, but there would only be \$206.76 left to withdraw on the 35th month.

Let's assume you place

\$100,000     in cell A1

0.015        in cell B1  (this is 1.5% and you can simply format this cell as %)

=B1/12       in cell B2  (this is the interest rate per month)

\$3000        in cell E1

Then the formula for calculating the number of months before a zero balance is reached is:

=LOG(B2/(E1/A1-B2)+1)/LOG(1+B2)

This yields 34.1 in the case you gave.  The decimal part indicates that you cannot withdraw a full \$3000 in the final (35th) month.

Keep Excelling.

Damon
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This topic answers questions related to Microsoft Excel spreadsheet (or workbook) stand-alone or Mircrosoft Office Excel including Excel 2003, Excel 2007, Office 2000, and Office XP. You can get Excel help on Excel formulas(or functions), Excell macros, charting in Excel, advanced features, and the general use of Excel. This does not provide a general Excel tutorial nor the basics of using a spreadsheet. It provides specific answers to using Microsoft Excel only. If you do not see your Excel question answered in this area then please ask an Excel question here

#### Damon Ostrander

##### Expertise

I have extensive experience with VBA programming in Excel 5 through Excel 2013. As a former aerospace engineer with a large aerospace corporation and consultant in a small defense technology services company, I have developed a wide range of applications in VBA, including simulations involving mixed-language programming, satellite orbit mechanics, graphics and animation, and real-time applications. I am interested in moderate to hard VBA-related questions only.

##### Experience

I have developed and taught several courses in Excel VBA programming and also VBA programming in Office 97, 2000, and 2007. I have developed a number of large technical applications in Excel VBA for use within the aerospace industry.

Education/Credentials
B.S. in Electrical Engineering and Computer Science, University of California, Berkeley.