A class last year budgeted €300 to paint a set for the school play. They listed every tin and every brush. They forgot one line: contingency. Midway through the job the timber split and they needed an extra €28 of board. The budget was already full. The show still went on — but two students paid for the board out of their own pockets.
Today you take the line items you already costed and turn them into a proper budget: categories, subtotals, a contingency line, and a grand total written to the right degree of accuracy. That finished sheet is Project Budget v2, and it goes straight into your MA1 portfolio.
A list of prices is not yet a budget. A budget groups every line into a category, totals each category, adds a contingency for the unexpected, and writes every figure to the accuracy the job needs.
| Concept | Why it matters | Example |
|---|---|---|
| Budget category — a labelled group of related line items (materials, consumables, delivery, contingency) | Lets you see at a glance where the money is going, and cut one group without touching the others | Materials (paint, primer, timber) kept separate from Consumables (rollers, tape, sandpaper) |
| Contingency — spare money, typically 10% of the materials total, for costs you have not met yet | One split board or a second tin of paint no longer blows the whole plan | Materials €241 → contingency 10% = €24.10 |
| Degree of accuracy — how precisely you write each figure (nearest cent, nearest euro, one decimal place) | A total written two different ways looks like two different answers; pick a rule and stick to it | Money to the nearest cent (€24.10); contingency rate as 10% or 10.0% |
| Subtotal and grand total — sum inside one category, then sum of every category including contingency | The grand total is the number you hold against the project ceiling | Materials €241 + Consumables €28 + Delivery €35 + Contingency €24.10 = €328.10 |
Below is a worked school-set paint budget already grouped. Read the three sections and the balance against the €450 ceiling.
Use the budget builder below. Load the starter example if it is not already there, then rebuild it so every line sits in the right category.
When the categories, contingency and balance all look right, leave the budget on screen — you will use the same figures in the next step.
Now lock the arithmetic in with short target puzzles. Each one uses real budget figures as the starter numbers. Build an expression that lands exactly on the target — that is the contingency, a category subtotal, or the grand total under the ceiling.
Work the first one with the class, then try the rest in pairs. You may use +, −, × and ÷. Do not reuse a starter inside one puzzle unless the prompt says you can.
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