The idea
Multiplication counts equal groups efficiently. An array arranges those groups into rows and columns. Division can ask how many are in each equal group, or how many groups can be made from a total.
Before you begin: Add equal amounts and count in twos, threes, fours, fives and tens.
There are four rows of five counters. Find the total, then share it equally among four people.
Each row contains five counters, so add five four times.
Write the equal groups as multiplication. Reading the columns gives a related fact with the same total.
Sharing the twenty counters among four people reverses the multiplication. Each person gets five.
A mistake to avoid
Equal groups must contain the same number of objects. Four groups of five is not four plus five.
Your turn.
Three bags each hold four apples. How many apples are there? How many are in each bag?
Show the solution
Three equal groups of four make twelve. Sharing twelve among three groups gives four in each.