Key Concepts
- Array multiplication
- Use place value for multiplication
Multiply by 1-digit numbers
What are 1–digit numbers?

The smallest one-digit number is 1 (one).
The greatest one-digit number is 9.
All the digits become numbers when used as a number.
Example 1: 2 digits by 1–digit multiplication.

Example 2: 2 digits by 1–digit multiplication.
Multiply 8 × 26.
Multiply the ones 8 × 6 = 48
Multiply the tens 8 × 20 = 160
Add the tens and ones.

Array multiplication
Example 1:
A Ferris wheel completes a rotation for 38 seconds. How many seconds in all would it take to complete 4 rotations?

Solution:
One way to record multiplication.


152 seconds will take to 4 rotations.
Example 2:
A polar bear climbs on a rock every morning to eat a breakfast of 29 fish. How many fish in one week will the polar bear eat?

Solution:
Multiply 29 × 7.


Polar bear eats 203 fishes during the week.
Use place value for multiplication
At Kelvin’s birthday party, all his 4 friends get a surprise goodie bag. 38 candies are in each bag. How many candies do his friends get in all?

Solution:
Another way to record multiplication
Step1:
Multiply by the ones.

Record the 2 ones.
Record the 3 tens.
Step 2:
Multiply by the tens.


His friends get 152 candies.
Example 2:
Charmin plays outside for 65 minutes in one day. How many minutes will she play in 8 days?

Solution:


She will get 520 minutes to play.
Example 3:
Tim bought 5 packs of balls. If each pack contains 134 balls, how many balls does Tim have in all?

Solution:
Multiply 134 × 5.
Step 1:
First multiply the ones.

Step 2:
Multiply the tens.

Step 3:
Multiply the hundreds

So, 134×5 = 670.
Tim has 670 balls.
Exercise
- Find each product. Estimate to check if your answer is reasonable.
307
× 2
553
× 3
- Find the product.
25
× 3
_________
_________
1172
× 4
- Use place value to explain each step to find 4 × 3, 678.

- Use the partial product model to find the product of 9 × 38

- Fill the missing numbers.

- Through the place value of multiplication, find the product.

- Ria ordered 9 boxes of fruits. There are 32 fruits in each box. How many fruits did ria order?
- A flashlight requires 2 batteries to function. How many batteries in all would 7 such
flashlights require? - Norah uses an ounce of butter to bake 9 cookies. How many cookies can she bake
with 18 ounces of butter? - A tour operator owns a small fleet of 8 cars of the same make. Each car is filled with
2 liters of engine oil. How many liters in all have been filled in the cars? - Vanessa sells 6 cakes every day. How many cakes will she sell in 20 days?
What have we learned
- Understand 1 digit numbers.
- Understand how to multiply by 1 digit through array model.
- Understand how to multiply by 1 digit through place value.
- Adding partial products.
- Identify the place value.
Concept Map

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