Quick q' about working with numbers

[bazza825]

Hi, i've just joined the group because i want to learn about the more
'in depth' facilities of excel (and also hopefully access in future).

I want to be able to calculate from a resultant calculation (does that
make sense?).
eg: £100 less 10% less 10%

Now the result should be 81 (because it's a percentage of a resultant
calculation)....

The only way i can do it is by using allsorts of empty cells and dump
numbers in it, but it's getting too complex with a quantity of
numbers...

I'm stuck, could anyone help please?

(In simple terms please, because i'm not a guru yet)

thanks in advance
barry

 

[vandenberg p]

Hello:

Algebra, not Excel.

=100*(1-0.1)*(1-0.1)
=100*(1-0.1)^2

Take your choice. As long as the two percentages are the same the
second is probably the choice. If the two percentage can be different
then the first is the choice.

Pieter Vandenberg



: Hi, i've just joined the group because i want to learn about the more
: 'in depth' facilities of excel (and also hopefully access in future).

: I want to be able to calculate from a resultant calculation (does that
: make sense?).
: eg: 100 less 10% less 10%

: Now the result should be 81 (because it's a percentage of a resultant
: calculation)....

: The only way i can do it is by using allsorts of empty cells and dump
: numbers in it, but it's getting too complex with a quantity of
: numbers...

: I'm stuck, could anyone help please?

: (In simple terms please, because i'm not a guru yet)

: thanks in advance
: barry


: --
: bazza825
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[bazza825]

Algebra, not Excel.

=100*(1-0.1)*(1-0.1)
=100*(1-0.1)^2

Many thanks for that It works fine, but i'd love to understand why
Also, what would i do if i had two completely different percentage
numbers (eg 15 and 4)?? Where would i put them?

Could you possibly explain it to me please? I dont understand (1-0.1)
or the ^... never was that good at math.

thanks again
barry

 

[Bob Phillips]

actually, it's arithmetic

=100*90%*90%

--

HTH

Bob Phillips

(remove nothere from the email address if mailing direct)

 

[pdberger]

As noted, these questions aren't so much Excel questions as algebra
questions, and getting used to formulating them in statements Excel
understands.
If you want 90% of something, you're really multiplying by 0.9 (which equals
1 minus 0.1 -- hence the first equation).
If you want to reduce by 15% and then 4%, you are really multiplying by 0.85
(1 minus 0.15) and then multiplying that result by 0.96 (1 minus 0.4).
Since you can put that all (and much, much more) into one equation, you can
write it as
A B
1 ## =A1*.85*.96

Try it.

HTH

 

[bazza825]

Hey, thanks all of you for that... i've tested it and it does indeed
work (not that i doubted any of it)

I couldn't understand (and still don't really) why i'd want/need to
express the 0.90 as (1-0.1)? If it's the same thing where's the benefit
of the latter?

thanks again
barry

 

[vandenberg p]

Hello:

There is no difference betweeen .9 and 1-.1 they are the same. The only
reason for using 1-.1 was to indicate the solution using the data you
supplied, in the format you supplied it, which was 10%. In your spreadsheet
you would probably put it in a discount percent, such as discounts
11% and 14%

So:

Cell A1: '1st Discount
Cell A2: '2nd Discount
Cell A3: 'Price
Cell A4: 'Discounted Price
Cell B1: .11
Cell B2: .14
Cell B3: 100
Cell B4: = B3*(1-B1)*(1-B2)

Finally if the both discount rates were the same the short way would be
to write it with an ^ which means to raise to a power. eg .9*.9 could be
written in a cell as =.9^2

Pieter Vandenberg


: Hey, thanks all of you for that... i've tested it and it does indeed
: work (not that i doubted any of it)

: I couldn't understand (and still don't really) why i'd want/need to
: express the 0.90 as (1-0.1)? If it's the same thing where's the benefit
: of the latter?

: thanks again
: barry


: --
: bazza825
: ------------------------------------------------------------------------
: bazza825's Profile: http://www.excelforum.com/member.php?action=getinfo&userid=33241
: View this thread: http://www.excelforum.com/showthread.php?threadid=530672