 Study P4 Mathematics Maths - Multiplication - Geniebook   # Multiplication

1. Multiplication of $$4-$$digit numbers by $$1-$$digit numbers
2. Multiplication by $$10$$ and its multiples
3. Multiplication of $$2-$$digit numbers by $$2-$$digit numbers
4. Multiplication of $$3-$$digit numbers by $$2-$$digit numbers

In Primary $$2$$ and $$3$$, we have learnt the multiplication tables of $$1$$ to $$10$$   Question 1:

Solve the following multiplication.

$$8 × 9 =$$ __________

1. $$54$$
2. $$56$$
3. $$64$$
4. $$72$$

Solution:

$$8 \times 9 = 72$$

$$(4) \;72$$

Question 2:

Solve the following multiplication.

$$18 \times 7 =$$ __________

1. $$124$$
2. $$126$$
3. $$134$$
4. $$136$$

Solution: $$(2) \;126$$

## 1. Multiplication Of 4-Digit Numbers By 1-Digit Numbers

The multiplication of $$4-$$digit numbers by $$1-$$digit numbers is similar to the multiplication of $$3-$$digit numbers by $$1-$$digit numbers.

Example:

$$1936 × 7 =$$ __________

Solution:

Step 1: Step 2: Step 3: Step 4: $$13 \,552$$

Question 1:

Solve the following multiplication.

$$3918 \times 5 =$$ __________

Solution: $$19 \,590$$

## 2. Multiplication By 10 And Its Multiples

When we multiply a whole number by $$10$$, we add one ‘$$0$$’ after the number.

For instance,

\begin{align*}​ 5 \times 10 &= 50 \\ 15 \times 10 &= 150 \\ 215 \times 10 &= 2150 \end{align*}

What do you think happens when we multiply a whole number to a multiple of $$10$$?

We express the multiple as a product of $$10$$ and a number.

Let’s try the following.

Example:

$$5 \times 30 =$$ __________

Solution:

We express $$30$$ as a product of $$3$$ and $$10$$.

\begin{align*}​ 5 \times 30 &= 5 \times 3 \times 10 \\ &= 15 \times 10 \\ &= 150 \end{align*}

$$150$$

Question 1:

Solve the following multiplication.

$$22 \times 10 =$$ __________

$$220$$

Question 2:

Solve the following multiplication.

$$51 \times 10 =$$ __________

$$510$$

Question 3:

Solve the following multiplication.

$$38 \times 50 =$$ __________

Solution:

 \begin{align*}​ 38 \times 50 &= 38 \times 5 \times10 \\ &= 190 \times 10 \\ &= 1900 \end{align*} $$1900$$

Question 4:

Solve the following multiplication.

$$94 \times 50 =$$ __________

Solution:

 \begin{align*}​ 94 \times 50 &= 94 \times 5 \times 10 \\ &= 470 \times 10 \\ &=4700 \end{align*} $$4700$$

Question 5:

Solve the following multiplication.

$$74 \times 60 =$$ __________

Solution:

 \begin{align*}​ 74 \times 60 &= 74 \times 6 \times 10\\ &= 444 \times 10\\ &= 4440 \end{align*} $$4440$$

Question 6:

Solve the following multiplication.

$$1059 × 90 =$$ __________

Solution:

 \begin{align*}​ 1059 \times 90 &= 1059 \times 9 \times 10 \\ &= 9531 \times 10 \\ &= 95 310 \end{align*} $$95 \,310$$

## 3. Multiplication Of 2-Digit By 2-Digit Numbers

Now, let’s multiply a $$2-$$digit number by a $$2-$$digit number.

Step 1:

We multiply the first number by the digit in the ones place of the second number.

Step 2:

We multiply the first number by the digit in the tens place of the second number.

Step 3:

Question 1:

Solve the following multiplication.

$$18 \times 12 =$$ __________

Solution:

Step 1:  Step 2:  Step 3: You can see $$12 = 10 + 2$$

\begin{align*}​ 18 \times 10 &= 180 \\ 18 \times 2 &= 36 \\ 180 + 36 &= 216 \end{align*}

$$216$$

Question 2:

Solve the following multiplication.

$$67 \times 38 =$$ __________

Solution: $$2546$$

Question 3:

Solve the following multiplication.

$$27 \times 31 =$$ __________

Solution: $$837$$

## 4. Multiplication Of 3-Digit By 2-Digit Numbers

The multiplication of $$3-$$digit numbers by $$2-$$digit numbers is similar to the multiplication of $$2-$$digit numbers by $$2-$$digit numbers.

Step 1:

We multiply the first number by the digit in the ones place of the second number.

Step 2:

We multiply the first number by the digit in the tens place of the second number.

Step 3:

Question 1:

Solve the following multiplication.

$$132 \times 18 =$$ __________

Solution:

Step 1: Step 2: Step 3: You can see, $$18 = 10 + 8$$.

\begin{align*}​ 132 \times 10 &= 1320 \\ 132 \times 8 &= 1056 \\ 1320 + 1056 &= 2376 \end{align*}

$$2376$$

Question 2:

Solve the following multiplication.

$$413 \times 26 =$$ __________

Solution: $$10 \,738$$

Question 3:

Solve the following multiplication.

$$634 × 38=$$ __________

Solution: $$24 \,092$$

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Time  Primary  Primary 1  Primary 2  Primary 3  Primary 4  English  Maths
Multiplication
Whole Numbers
Line Graphs
Time
Multiplication And Division
Decimals
Model Drawing Strategy
Division
Fractions
Factors And Multiples
Area And Perimeter 1  Science  Primary 5  Primary 6  Secondary  Secondary 1  Secondary 2  Secondary 3  Secondary 4      