Spreadsheets

Sudhakar has the mid-term marks of 22 students in 6 subjects: 132 numbers. He wants each student's total and each subject's class average. With a calculator, that is a long afternoon with many chances to slip.

A spreadsheet is made for this. It is a digital notebook of rows and columns of small boxes called cells. Each cell holds some text or a number.

Every cell has an address. Columns are lettered A, B, C, … and rows are numbered 1, 2, 3, … So a cell is named by its column letter and row number: E5, B7, D2. Farooq's Mathematics mark is in E5: column E is Maths, row 5 is Farooq.

The real power: a cell can hold a formula, not just a value. Type a formula and the spreadsheet works it out, and works it out again by itself whenever the data changes.

To talk about a run of cells, write Start:End. So B3:G3 means every cell from B3 to G3: Nagesh's marks in all six subjects. B7:D7 means Gowri's marks in just Odia, Telugu and English.

Columns work the same way: D2:D6 is the English marks of the first five students.

Two formulas do most of the work:

• =SUM(B3:G3) gives Nagesh's total across all subjects.
• =AVERAGE(B7:D7) gives Gowri's average across those three subjects.

So the class average in one subject is =AVERAGE of that subject's column, over all the student rows. Write it once for each subject, and a question like 'is the class average in Odia higher than in Telugu?' takes seconds, not an afternoon.