24 Part 1: The World of Numbers
Basic Multiplication Facts
×123456789
1 123456789
2 2 4 6 8 10 12 14 16 18(^3369121518212427)
(^44812162024283236)
(^551015202530354045)
6 61218243036424854
7 71421283542495663
8 81624324048566472
9 91827364554637281
The first column and top row show the single digit numbers. Each cell shows the product of the
digits that start its row and column.
Once you’ve memorized the multiplication facts, you can take advantage of what you know about
our place value system to handle larger numbers. Let’s start with something not too large. Let’s
multiply 132 v 3.
You know that 132 means 1 hundred and 3 tens and 2 ones, and you know that multiplying by 3
is the same as adding 132 + 132 + 132. Instead of all that adding, you can multiply each digit of
132 by 3, using the 3 times table, and you get 396 or 3 hundreds, 9 tens, and 6 ones. Each digit,
each place, gets multiplied by 3. 132 v 3 = 396.
Now let’s multiply 594 v 2. You have 5 hundreds, 9 tens, and 4 ones, and you want to multiply
by 2. That should give us 10 hundreds, 18 tens, and 8 ones, but that means that you again face
that problem of having a two-digit answer and only a one-digit place to put it. Just as you did
with some of our addition, you’re going to need to carry.
Once again, you want to tackle that work from right to left. So, in this example, you start
with 2 v 4 = 8 and that’s a single digit, so it can go in the ones place of the answer. Next, you
multiply 2 v 9 = 18. That’s 18 tens. You break that into 1 group of 10 tens and another 8 tens,
or 1 hundred and 8 tens. The 8 can go in the tens place of your answer, but you’ll hold on to the
1 hundred for a minute. Put a little 1 over the 5 to remind yourself that you have that 1 hundred
waiting. One more multiplication, this time 2 v 5 = 10 hundreds, and then you’ll add on the