In this Grade 4 lesson from Saxon Math Intermediate 4, students learn multiplication facts for 9s, 10s, 11s, and 12s, with a focus on recognizing digit patterns to make recall faster and easier. For the 9s, students discover that the first digit of each product is one less than the factor being multiplied, and the two digits always sum to nine. The lesson applies 10s, 11s, and 12s facts in real-world measurement contexts, such as converting centimeters to millimeters and feet to inches.
Section 1
📘 Multiplication Facts: 9s, 10s, 11s, 12s
Also notice that the two digits of each product add up to nine.
Next, you’ll apply this pattern-finding skill to master multiplication facts for 9s, 10s, 11s, and 12s through practice problems.
Section 2
9s multiplication facts
When multiplying by nine, the first digit of the product is one less than the number being multiplied, and the sum of the product's two digits is nine.
Multiplying by nine is a neat trick! First, subtract one from the number you are multiplying by nine to find the first digit of the answer. Then, find the number you must add to that first digit to get a total of nine. That number is the second digit of your answer.
Section 3
10s multiplication facts
To find the product of a whole number and 10, we simply attach a zero to the end of the whole number.
Multiplying by 10 is the easiest trick in the book. Just take the number you are multiplying and add a zero to the end of it. This works because our number system is based on groups of ten, so multiplying by 10 moves every digit one place over to the left.
Section 4
11s multiplication facts
For single-digit numbers, the product of the number and 11 is the digit repeated twice.
Multiplying by 11 with a single digit is like seeing double! Just take the digit you are multiplying and write it down twice to get your answer. For example, multiplying by 3 gives you 33. This cool pattern makes these facts super easy to remember and solve in a flash. It's a fun party trick!
Section 5
12s multiplication facts
The multiplication facts for 12 can be found by skip-counting by 12s or by thinking of them as dozens.
The 12s facts might seem tough, but think of them as groups of a dozen, like a dozen eggs! You can master them by skip-counting out loud: and so on. Another pro tip is to multiply the number by 10, then multiply it by 2, and add those two results.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter
Expand to review the lesson summary and core properties.
Section 1
📘 Multiplication Facts: 9s, 10s, 11s, 12s
Also notice that the two digits of each product add up to nine.
Next, you’ll apply this pattern-finding skill to master multiplication facts for 9s, 10s, 11s, and 12s through practice problems.
Section 2
9s multiplication facts
When multiplying by nine, the first digit of the product is one less than the number being multiplied, and the sum of the product's two digits is nine.
Multiplying by nine is a neat trick! First, subtract one from the number you are multiplying by nine to find the first digit of the answer. Then, find the number you must add to that first digit to get a total of nine. That number is the second digit of your answer.
Section 3
10s multiplication facts
To find the product of a whole number and 10, we simply attach a zero to the end of the whole number.
Multiplying by 10 is the easiest trick in the book. Just take the number you are multiplying and add a zero to the end of it. This works because our number system is based on groups of ten, so multiplying by 10 moves every digit one place over to the left.
Section 4
11s multiplication facts
For single-digit numbers, the product of the number and 11 is the digit repeated twice.
Multiplying by 11 with a single digit is like seeing double! Just take the digit you are multiplying and write it down twice to get your answer. For example, multiplying by 3 gives you 33. This cool pattern makes these facts super easy to remember and solve in a flash. It's a fun party trick!
Section 5
12s multiplication facts
The multiplication facts for 12 can be found by skip-counting by 12s or by thinking of them as dozens.
The 12s facts might seem tough, but think of them as groups of a dozen, like a dozen eggs! You can master them by skip-counting out loud: and so on. Another pro tip is to multiply the number by 10, then multiply it by 2, and add those two results.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter