Idea 1of 24
Rows times columns
How can you count 56 lights without counting one by one?
Today you'll discover
- what an array is
- how rows and columns make a multiplication
- what a product is
Think first7 rows of lights, 8 in each row
There are 7 rows of 8 lights. How many lights are there?
Decide first, then press Next. Count the rows, then how many are in one row.
A block of dots in 7 rows of 8. Then the words 7 rows and 8 in each row appear beside it, with 7 × 8 on the right; running totals 8, 16, 24 up to 56 appear at the end of each row; then 7 × 8 = 56. The last step shows 6 rows of 9 chairs.
See the whole ideathe big idea and the key word, in one place
The big idea
An array's rows times the number in each row gives how many there are: the product.
Arrays around youEgg cartons, muffin tins and rows of desks are arrays: equal rows you can count by multiplying.
Easy to get wrongDo not add the rows and the row length. 7 + 8 = 15 counts one row and one column, not every light.
Key words
- array
- things set out in equal rows, like 7 rows of 8 lights
- product
- the answer to a multiplication: in 7 × 8 = 56, the product is 56
Ready to use it?
- Write the multiplication an array shows.
- Find how many are in an array of rows.