## 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.