Chameleon text and number in spreadsheets. Watch out for this trap.

In Excel, a text is sometimes treated as a text and sometimes as a number. This can be quite confusing and can lead to wrong calculations.

Users have to be aware of this and ensure that the cells in a summation are numbers.

Here is an illustration.

A1 and A2 contain numbers 11 and 12.
A3 contains a text "13".

In an addition where each cell is explicitly added, as in cell B4, "13" is treated as the number 13.

But.

In a sum formula, as in cell B5, "13" is treated as a text and is not added to the sum.

Spreadsheet users have to be very careful that each cell in a summation is a number. Otherwise, the cell "number" will not be added.

This chameleon quality applies to some other formulas also.