An array is equal groups lined up in rows. Every row has the same number, like seats in a theater or eggs in a carton.
Por qué funciona
Each row is a group, and every row is the same size. So an array with 4 rows of 6 is 4 groups of 6, which is $4 \times 6$. You can count by rows instead of by dots: 6, 12, 18, 24.
Idea clave
An array with $r$ rows and $c$ in each row shows $r \times c$. Rows go across; columns go up and down.
Ejemplo resuelto: Count by rows
How many dots are in an array with 4 rows of 6?
- Each row has 6. There are 4 rows.
- Count by 6s, one count for each row: 6, 12, 18, 24.
- So $4 \times 6 = 24$.
Respuesta: $24$ dots
Ejemplo resuelto: Seats
A theater has 7 rows with 5 seats in each row. How many seats?
- 7 rows of 5 is $7 \times 5$.
- Count by 5s seven times: 5, 10, 15, 20, 25, 30, 35.
Respuesta: $35$ seats
Error común
Counting every dot one by one. It works for small arrays, but it is slow and easy to lose your place. Find the size of one row, then count by that number once for each row.