Calculating percentages using numbers

Question

Hi there, 
I hope someone out there can help me but how do I calculate the percentage of two numbers using Numbers. For example £4000 incoming and £1650 outgoings - How do  I get the spreadsheet to work out the percentage and input this number into the fields?  This is really painful trying to work it out. Thanks

Answer 1

Hi Adrian,
You wrote: "I need to do this with 2 column actually A and B, both column need to be added by that 5%, I think this only possible"
If I'm reading the description of your table correctly, column A shows the number of units, column B the price of each unit, and column C the price of that quantity of units.
If you increase the unit price by 5%, that will also increase the total price of n units by 5%, provided you multiply the quantity by the new unit price instead of the old unit price.
Here's a step by step:
Original table:
Formula in C2, and filled down column C: =A*B
Add a new column (D) to hold the formula for the increased price.
D2, and filled down: =B*(1+5%)
With the cells shown still selected, Copy (command-C)
Now select cell B2, and go Edit > Paste Values (Numbers '09) or Edit > Paste Formula Results (Numbers 3)
Results should be as shown below:
(Note that column C has been recalculated to show the results of a 5% increase in unit prices. Column D (labelled "temp") has also been recalculated to show what the unit prices would be after a second 5% increase. the last step is to delete this column, leaving us with the original table, but with unit prices increased by 5%:
In practice, you would probably NOT do this on the actual invoice. Item names (or numbers) and the unit prices of those items would be kept on a price list, separate from the invoice, and the price would be looked up by the Invoice table when the item name or number was entered. The table would be used as an invoice generator, and the completed invoices either printed or 'printed' as pdf files as each was generated.
Price changes would be made on the price list, either individually, or geerally as done here. Note that the new prices would affect new invoices AND any existing invoices still connected to the price list (which is why each is 'printed' to separate it from the calculating document). Here's a simple example using a price list as a lookup table. Item Number and Quantity are entered on the invoice. The rest is added by formulas.
Formulas:
Price List has no formulas.
Invoice:
C2 and filled right to column D and down to row 6:
=IFERROR(VLOOKUP($B,Price List :: $A:$C,COLUMN()-1),"")
In row 6, the empty cell in column A will cause a "could not find" error. IFERROR catches this and places a null string in C6 (and in D6).
E2 and filled down to E6: =IF(LEN(D)<1,"",A*D)
LEN(D) returns the length (in number of characters) of the contents of the cell on the same row of column D. If the cell is empty, or contains a null string (as in row 6), the length is zero, and IF will place a null string in column E.
SUM, in row seven, interprets text (including a null string) as zero, so this does not affect the sums in coumns A and E.
Row 7 is a Footer Row. Formulas referencing a whole column ignore values in Header and Footer rows, making it possible to place the formulas below where they are.
A7: =SUM(A)
E7: =SUM(E)
Regards,
Barry