Video: Multiplying Two-Digit Numbers by One-Digit Numbers Using Column Multiplication

Solve the following: 23 × 2 = _

02:29

Video Transcript

Solve the following: 23 times two equals what.

Now, perhaps you’ve learned your two times tables facts up to 10 times two or maybe even 12 times two. But what happens when we need to multiply larger numbers by two? Well, in this question, we’ve got a two-digit number, 23, and we need to multiply this by two. And we can see, first of all, that the way that these numbers have been written they’re on top of each other. And by writing the numbers in columns like this, it helps us to see the tens and the ones digit separately. Let’s begin by thinking about the tens and the ones in our first number. The number 23 is made up of two tens and three ones. And to solve the problem, we can multiply these two parts of our two-digit number separately.

We can start by looking at the ones. What are three ones multiplied by two? Well, we know that three times two is six. So in our column addition, we can write the digit six in the ones place of our answer underneath the equal sign. Our answer is going to have six ones in it. Now that we’ve multiplied the ones part of our number, we can multiply the tens part. And if we look at the tens column in the number 23, we can see the digit two. And we must always remember, although it looks like we’re multiplying two by two, what we’re really multiplying is two 10s by two because the two is in the tens place.

You know, as long as we understand that we’re multiplying two 10s, we can use the fact two times two to help us. We know that two times two is four. So two 10s times two equals four 10s. And we can show this by writing the digit four in the tens place. And if we look at both our place value counters that we’ve used to help us but also the column multiplication, we can see the same answer. It has four tens and six ones. We’ve found the answer to 23 times two by using the column method. Although we used place value counters to help us model what we’re doing, we didn’t have to. 23 multiplied by two equals 46.

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