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.