Today you will
- lock one cell so a formula can fill down without breaking
- add a % of Total column to {{code:05_project_budget}}
- see which cost takes the biggest share of your budget
Warm-up
Cell {{cell:C7}} holds your total. You type {{formula:=C2/C7}} and drag it down one row. Does the {{cell:C7}} part stay on the total, or does it move to {{cell:C8}}?
A relative reference, like {{code:C2}}, moves down a row when you fill a formula down.
An absolute reference, like {{code:$C$7}}, has dollar signs, so it stays locked.
The fill handle is the small square at a cell's corner. You drag it to copy a formula.
A fill-down break is when the total slides to an empty cell and shows {{code:#DIV/0!}}.
Example
Aoife's hoodie budget has its €320 total in {{cell:C7}}. The formula {{formula:=C2/$C$7}} divides every row by that total.
You will build Aoife's sample budget, watch a formula break, and then fix it with a locked total. Follow the steps in the box below.
You will see {{code:#DIV/0!}} partway through, and that is expected. You will fix it when you lock the total.
| Item | Category | Cost (€) | % of Total |
|---|---|---|---|
| Hoodie blanks | Materials | 120 | 37.5% |
| Screen print kit | Materials | 85 | 26.6% |
| Instagram ads | Marketing | 40 | 12.5% |
| Packaging | Materials | 25 | 7.8% |
| Market stall fee | Events | 50 | 15.6% |
| Total | 320 |
Type the first three columns. The last column shows the answers you should get.
Common issues
- The lower rows show {{code:#DIV/0!}}. The total slid off its cell. Add dollar signs to the total in the first formula and fill down again.
- It still breaks after you add {{code:$}}. You need two dollar signs, like {{code:$C$7}}, one before the letter and one before the number.
- You see 0.38 instead of 38%. Select the column and click {{btn:%}}.
Independent Practice
- Check that your Cost column has a Total with a SUM formula. Add one if it is missing.
- Click your total cell and write its address on a sticky note, for example C12.
- Type % of Total in the next free column.
- In the first item row, divide the cost by your total with dollar signs, for example {{formula:=C2/$C$12}}.
- Ask your teacher to check it, then fill it down and click {{btn:%}}.
- My % of Total column sits beside my items.
- Every row shows a percentage, and they add up to about 100%.
- The percentages update when I change one cost.
- No errors show in the column.
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