# Really Stupid Math Question

I am mathematically challenged. I need the Excel formula to determine the final number of 15% of 27. I can do it in my head (10% of 27 added to half of that subtracted from 27) but it’s not working out in Excel. I’m getting a negative number, where I know I could just encase the whole thing in absolute value, but I would like to have the correct equation. Thanks.

=27 * 15 / 100 should do it, right?

Are you talking about 27 minus fifteen percent?

=27*.85

Or 15% of 27?

=27*.15

H.

Percents are just fractions of a 100, so 15% is equal to .15, therefore, just multiply 27 *.15.

Brian, that shows the discount but I needed the final price, thanks. H. thanks, the .85 was what I was doing wrong.

Thanks again, brain short.

For a typical excel calculation you will probably want to round it off, too. ROUND function will do the trick.

. . . and thank you, for finally asking a math question I could answer. The crap some of these people know around here leaves me boggling.

H.

Lord, don’t get me started on that. Because I’ll just tell really boring stories about people not realizing where and when they were losing precision. I now have a blanket policy that you always always round always everything always to always the precision you always decided always at the always outset you were going for. Always.

Wahhh? Round at the end, not before. Don’t give up any more precision than you have to.

You’d think that, right? But the thing is, when people come in in the middle of chains of linked functions to take the value at that point and then they don’t understand why their math comes out marginally different than the math at the end of the thirty seven steps they didn’t do and try to blame it on the database. Precision is totally for science - not for economics and industrial forecasting.

Math class is tough.

Well Disgaea 4 came out today and my son works at Gamestop. He can get a 15% discount on the software so I was trying to work out exactly how much a new PS3 and and the games I wanted would work out to. So the equation ended up being =(SUM(D1:D5))*0.85 using a currency format which should round appropriately.

Unfortunately it does not look as if it would be feasible for me to get one at this time. So I’ll just have something to look forward to after the property taxes, car insurance and house insurance get paid.

I was also wondering why I was having trouble with it when I did this kind of stuff in school. But I now remember that we used a financial calculator in class and that’s a different method since you just press the % key.

Even though it has already been answered…
27 minus 15 percent of 27
so 27 - 0.15*27
or 27 * (1-0.15)

Qt3, we’re getting a flavor of what a first date with Brian would be like. ;)

Why are you using Excel to do this? What you should be using is Maya.

Also, the plane takes off.

… or a gasp calculator.

Excel is handy to do an inventory list and show discounted prices en masse (even at different percentages off), but for two items?

(Please note, I’m just giving you a hard time for the fun of it)

And how much did you round that, exactly?

It’s also very encouraging that someone with an MBA who worked at NASA can’t handle basic percentage calculations or use Excel.