Word Processing and Spreadsheet
Primary 6 · Science and Elementary Technology
Word Processing and Spreadsheet
Lesson 6 of 6
16 min
Let's begin
Niyonzima keeps the accounts for the school cooperative, which sells avocados, bananas and maize cobs. Adding up thirty numbers on paper takes him a long time, and one small mistake spoils the whole total.
A spreadsheet can do the same sums in a blink, and if one number changes, it works out the answer again by itself.
A formula is an instruction that tells the spreadsheet to calculate something. Every formula starts with an equals sign (=). Without it, the spreadsheet thinks you have typed ordinary text.
| Operation | Symbol | Example | Meaning |
|---|---|---|---|
| Addition | + | =A1+B1 | add A1 and B1 |
| Subtraction | - | =B2-C2 | take C2 away from B2 |
| Multiplication | * | =B3*C3 | multiply B3 by C3 |
| Division | / | =D4/B4 | divide D4 by B4 |
Spreadsheets use * for multiplication because the keyboard has no × key. The letter x does not work.
The cell shows the answer, and the formula bar shows the formula. Use cell references rather than typing the numbers themselves: then, if a number changes, the answer updates automatically.
A function is a ready-made formula.
The colon (:) means "from ... to ...". A comma means "and": =SUM(A1,B1) adds only A1 and B1. In some language settings you type a semicolon (;) instead of a comma. The Σ (AutoSum) button can write a SUM formula for you.
| A | B | C | D | |
|---|---|---|---|---|
| 1 | Item | Price (Frw) | Number sold | Total (Frw) |
| 2 | Avocado | 200 | 15 | =B2*C2 → 3000 |
| 3 | Banana | 100 | 24 | =B3*C3 → 2400 |
| 4 | Maize cob | 300 | 6 | =B4*C4 → 1800 |
| 5 | Grand total | =SUM(D2:D4) → 7200 |
The average sale per item is =AVERAGE(D2:D4), which gives 2400. Now suppose 20 avocados were sold, not 15. Niyonzima changes C2 to 20, and D2 becomes 4000 and D5 becomes 8200 on their own. That is the power of formulas.
Just as in Mathematics, multiplication and division are done before addition and subtraction. Use brackets to do something first: =(B2+B3)*2 adds first, then doubles.
Tip
No equals, no maths! Every formula begins with =, and * means multiply.
Do these on a computer if you can, or work them out in your book.
A1 holds 45 and B1 holds 15. What will each formula show? =A1+B1, =A1-B1, =A1*B1, =A1/B1
Answer: 60, 30, 675 and 3.
Write a formula to add all the numbers from C2 to C10.
Answer: =SUM(C2:C10)
Keza typed B2+B3 in a cell and it just shows B2+B3. What went wrong?
Answer: She forgot the equals sign. It should be =B2+B3.
Marks of 60, 70 and 80 are in cells B2, B3 and B4. Which formula finds the average, and what is the answer?
Answer: =AVERAGE(B2:B4), which gives 70.
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