KJSEA 2025 Maths Q8 — Order of a Matrix (Grade 9)
Published
The Question
“A matrix shows the results of two football teams. Determine the order of this matrix, where the options include 2 by 5 (option D).”
Recall what the order of a matrix means
The order of a matrix tells you its size. It is written as the number of rows multiplied by the number of columns. The important rule is that you always state the rows first and the columns second, so the order looks like rows by columns.
Count the rows
Rows are the horizontal lines of entries, read from left to right and stacked going down the page. In this matrix showing the two football teams, there are two horizontal lines of numbers, so there are two rows.
Count the columns
Columns are the vertical lines of entries, read from top to bottom and moving across the page. Counting across this matrix, there are five vertical lines of numbers, so there are five columns.
State the order
Put the counts together in the correct order: rows first, then columns. Two rows and five columns gives an order of two by five, which matches option D.
Final Result
The order of the matrix is 2 by 5, which is option D.
Why this method works
A matrix is just an arrangement of numbers in a rectangular grid, and its order records the shape of that grid. Because a grid is fully described by how many rows and how many columns it has, those two counts completely fix its size. Mathematicians agreed to always write rows before columns so that everyone reads the same order the same way; without that agreed order, 2 by 5 and 5 by 2 would be confused, even though they describe differently shaped grids.
Two rows across each holding five entries gives 2 times 5, which is 10 entries in total — consistent with a 2 by 5 grid.