No history yet

Multiplication and Division

Multiplication as a Shortcut

Multiplication is simply a fast way of doing repeated addition. If you buy 4 cartons of eggs and each carton has 12 eggs, you could add 12 + 12 + 12 + 12 to find the total. Or, you could multiply.

This idea of grouping is the core of multiplication. Instead of adding the number 12 four times, you can just say you have 4 groups of 12. The result is the same, but it's much quicker to write and solve.

4×12=484 \times 12 = 48

To make multiplication fast, we use multiplication tables. These tables list the results for multiplying small numbers, usually from 1 to 10 or 1 to 12. Knowing these facts by heart is a huge advantage, as it makes solving more complex problems much smoother.

Lesson image

Don't try to memorize the whole table at once. Focus on one number at a time. Start with the 2s, 5s, and 10s, as they have easy patterns. Then move on to the 3s and 4s. You'll find that many facts repeat, like 3×43 \times 4 is the same as 4×34 \times 3, which cuts down on what you need to learn.

Tackling Bigger Numbers

Memorizing tables is great for single-digit numbers, but what about multiplying something like 45×1245 \times 12? For this, we use a method called long multiplication. It breaks the problem into smaller, manageable steps using the multiplication facts you already know.

You multiply one digit at a time and then add the results. Let's walk through an example.

First, we multiply 45 by 2 (the ones digit of 12), which gives us 90. Next, we multiply 45 by 10 (the tens digit of 12), which gives us 450. Finally, we add these two results together: 90+450=54090 + 450 = 540. So, 45×12=54045 \times 12 = 540.

Division as Sharing

Division is the opposite of multiplication. It's about splitting a whole into equal parts. Think of it as repeated subtraction. If you have 20 cookies and want to know how many friends you can give 4 cookies to, you can subtract 4 over and over.

204=1620 - 4 = 16 (1 friend) 164=1216 - 4 = 12 (2 friends) 124=812 - 4 = 8 (3 friends) 84=48 - 4 = 4 (4 friends) 44=04 - 4 = 0 (5 friends)

You subtracted 4 five times, so 20÷4=520 \div 4 = 5. This shows the strong link between division and subtraction.

Just as multiplication is a shortcut for addition, division is a shortcut for subtraction.

For larger numbers, like 168÷7168 \div 7, repeated subtraction would take too long. This is where long division comes in. It's a systematic way to find out how many times one number fits into another, one digit at a time.

Here's how to solve 168 ÷ 7:

    24
   ___
7 | 168
  - 14  (7 goes into 16 two times)
    --
     28 (Bring down the 8)
   - 28 (7 goes into 28 four times)
     --
      0 (No remainder)

We first see how many times 7 goes into 16. It goes in 2 times, which is 14. We subtract 14 from 16 to get 2. Then we bring down the next digit, 8, to make 28. How many times does 7 go into 28? Exactly 4 times. So, 168÷7=24168 \div 7 = 24.

Multiplication and division are essential for everyday tasks, from splitting a bill at a restaurant to figuring out how many tiles you need for a floor. Mastering them opens the door to more advanced math.

Quiz Questions 1/6

Multiplication can be described as a shortcut for which of the following?

Quiz Questions 2/6

A school bus has 8 rows of seats, and each row can fit 4 students. What is the total number of students the bus can carry?

Now you have the basics down.