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Multiply by 1-Digit Numbers

Sep 20, 2022

Key Concepts

  • Array multiplication
  • Use place value for multiplication

Multiply by 1-digit numbers 

What are 1–digit numbers?  

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 1

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. 

Partial products 

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? 

Ferris wheel


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?  

A polar bear


Multiply 29 × 7.  

Multiply 29 × 7.  
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? 

Kelvin’s birthday party


Another way to record multiplication 


Multiply by the ones. 


Record the 2 ones. 

Record the 3 tens. 

Step 2: 

Multiply by the tens. 

Step 2: 
standard algorithm

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? 

Charmin plays



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?  

5 packs of balls.


Multiply 134 × 5. 

Step 1: 

First multiply the ones. 

Step 1: 

Step 2:  

Multiply the tens. 

Multiply the tens.

Step 3:  

Multiply the hundreds 

Multiply the hundreds

So, 134×5 = 670. 

Tim has 670 balls. 


  • Find each product. Estimate to check if your answer is reasonable.  


×   2


×   3

  • Find the product.


× 3




×    4

  • Use place value to explain each step to find 4 × 3, 678.
Use place value to explain each step to find 4 × 3, 678.
  • Use the partial product model to find the product of 9 × 38
Use the partial product model to find the product of 9 × 38
  • Fill the missing numbers.
Fill the missing numbers.
  • Through the place value of multiplication, find the product.
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

Concept Map


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