Sizu Riatto
Algebra · Chapter 22

Spreadsheet Formula Builder

Every spreadsheet formula is algebra with cell names for letters. Fix the cells that shouldn’t move, and the column fills itself correctly.

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Opens on Chapter 22’s example: Sanjay’s quote: $0.40 a sheet plus a $12 setup, for 100, 250 and 600 sheets.

1. A quote column
2. A price for a target margin
3. A what-if table
4. A countdown
5. Minutes to pay
Enter your numbers, then press Work it out.

How it works

A quote is rate × quantity + fee, so the cell formula is =A2*$E$1+$F$1. The $ signs fix a cell so it doesn’t move when the formula is dragged down; without them, the next row looks one cell lower for the fee, finds an empty cell and quietly drops it. A target margin is a share of the price, not of the cost: (price − cost) ÷ price = margin, so price = cost ÷ (1 − margin); adding the margin to the cost (a markup) falls short. A what-if column runs one formula over several prices; break-even is where profit is zero. A countdown is start − use × days. Minutes must become hours before multiplying by an hourly rate.

From the book, Chapter 22. 100, 250 and 600 sheets cost $52, $112 and $252; with the fee cell not fixed, 250 sheets shows only $100. A $6 item at a 40% margin sells for $10 ($4 margin); a 40% markup gives $8.40, only 28.6%. Prices $4 to $8 make $10 to $210, breaking even at $3.80. Paper runs down to the reorder level on day 10 (2,550 left after 7). 240 minutes is 4 hours, $88, not $5,280. Every chapter and its calculator →

Numbers can be typed as 1,450, $38, 0.40, 12%, 1/6 or 2 3/8. The algebra is done with exact fractions, so 1/3 stays 1/3; decimals are rounded half up, the way the book rounds. Everything stays in your browser: no sign-up, nothing stored or sent.