seegongsik
Grade 2 (age 7-8)

grade 2 Multiplication Basics

Introduction to Multiplication

Multiplication is a short way to write adding the same number again and again. If there are 3 candies on each of 4 plates, you could count 3 + 3 + 3 + 3, but writing it as 3 × 4 is quicker. Here 3 × 4 means 3 taken 4 times, and the times sign is ×. Change how many are in each row and how many rows there are, or how many are in each group and how many groups, and the repeated sum and the product come out the same.

Adding the same number again and again

🍎 Sharing apples on plates
①You put 3 apples on each of 4 plates
②3 + 3 + 3 + 3 = 12 adds the same number four times
③Writing that as 3 × 4 = 12 is multiplication

Multiplication as an array

3
4
💡 Arrays make it easy
①The number to the left of each row shows how many are in that row
②Under the picture, that number is added once for each row
③How many in each row × number of rows = how many in all
④× is read "times"
⑤4 × 3 and 3 × 4 have the same answer

Counting in groups

5
3
🎁 Counting in groups
①Counting equal groups is called counting in groups
②Each circle is one group, and the number under it is how many are in the group
③3 groups of 5 is 5 × 3 = 15
④You can find the total quickly without counting one by one

Wrap-up

What multiplication means
adding the same number again and again = multiplication
3 + 3 + 3 + 3 = 3 × 4 = 12
Reading a multiplication fact
3 × 4 = 12 → 'three times four equals twelve'
× is the times sign
Commutative property
3 × 4 = 4 × 3 = 12
You get the same answer in either order
🎯 Remember
①Multiplication means adding the same number again and again
②Thinking of an array, with how many in each row and how many rows, makes it easier
③We write it with the sign ×
④Switching the order gives the same answer (commutative property)
⑤Multiplication lets you count large amounts quickly

Examples and unit check

Example 1
Each plate has 4 apples. If there are 3 plates, how many apples are there in all?
1
Add 4 three times: 4 + 4 + 4.
2
As a multiplication, that is 4 × 3 = 12.
▸ 12 apples
Adding the same number many times can be written simply as multiplication.
Example 2
5 × 3 = 15. Use this to find 3 × 5.
1
In multiplication, switching the order gives the same answer.
2
So 3 × 5 = 5 × 3 = 15.
▸ 15
3 × 5 and 5 × 3 have the same answer (the commutative property of multiplication).
Unit check
Which multiplication matches 6 + 6 + 6 + 6?
①6 × 3
②6 × 4
③4 + 4 + 4 + 4
④6 + 4
▸ ② 6 × 4
1
6 is added 4 times, so it is 6 × 4.
2
6 × 4 = 24, the same as 6 + 6 + 6 + 6 = 24.
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Addition & Subtraction with Carrying
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Multiplication Table

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