A Student's Guide to Early Middle School Algebra Problems (With Worked Examples)
Mathnasium tutors explain early middle school algebra, expressions, equations, word problems, and inequalities, each with a worked example.
Have you ever noticed how house numbers along a street follow a predictable pattern—like skipping by twos as you walk down the block? After we spot the pattern, we can easily predict the next house number. Number patterns in math work the same way!
Mathnasium tutors break down how to spot the rule behind any number sequence and use it to figure out the numbers that come next.
Number patterns are sequences of numbers that follow a certain rule and are arranged in a particular order.
We encounter two types of number patterns: arithmetic and geometric.
Arithmetic patterns/sequences, also called linear patterns, are sequences where we add or subtract the same amount every time.
To check if we are working with an arithmetic pattern, we take a look at the difference between consecutive terms and confirm it stays the same throughout.
Take the sequence 3, 7, 11, 15, 19. We add 4 each time, and the sequence climbs at a steady, even rate.
Geometric patterns/sequences, also called exponential patterns, are sequences where we multiply or divide by the same number each time.
Here, we check the ratio between consecutive terms. If it stays the same, we’re talking about a geometric pattern.
For example, in the sequence 2, 6, 18, 54, 162, we multiply by 3 each time. By the fifth term, we are already at 162, and the rapid growth rate is easy to spot, which earns it the name exponential pattern.
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Finding the rule in a number sequence means examining how the terms relate to each other and deciding which operation connects them. We’ll work through four examples to get a clear picture of how the process works for each of the four operations.
First, we check if the sequence is going up or down, and in our case it is going up, which means we are either adding or multiplying.
We can see that the numbers are climbing at a steady pace, and that constant growth signals addition.
Next up, we figure out the difference between each term by using the opposite operation. From each number, we subtract the number before. The result is 5.
Our rule here is: add 5 each time.

As the sequence is going down, we know we are looking at a pattern that involves subtraction or division.
The numbers are decreasing steadily, so the operation is subtraction.
Check the difference between terms: 30 - 24 = 6, 24 - 18 = 6, 18 - 12 = 6, 12 - 6 = 6.
The rule is: subtract 6 each time.

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After we’ve established that the sequence is going up, it is easier to pin down the operation and identify the rule.
Take a closer look at how the numbers are behaving. They are growing very fast, which points us towards multiplication, not addition.
To measure the ratio, we divide each term by the one before it. The result is always three.
We are ready to identify the rule: multiply by 3 each time.

This sequence is going down, so we need to see if the operation is division or subtraction.
The numbers are shrinking at a very rapid pace, which points to division.
To check the ratio, divide each term by the one before it: 48 ÷ 96 = 0.5 (or \(\Large\frac{1}{2}\)), 24 ÷ 48 = 0.5 (or \(\Large\frac{1}{2}\)), and 12 ÷ 24 = 0.5 (or \(\Large\frac{1}{2}\)). We’re dividing the numbers by 2.
Alternatively, divide each term by the subsequent one to find the scale factor: 96 ÷ 48 = 2, 48 ÷ 24 = 2, and 24 ÷ 12 = 2.
We see that the rule is to divide by 2 each time.

After we identify the rule, extending a number pattern simply means applying that rule step-by-step to find the next terms in the sequence.
Take the sequence 7, 13, 19, 25.
We follow the rule identification process to confirm the difference between terms; in this case, it’s: add 6 each time.
After that, we extend forward: 25 plus 6 gives us 31, 31 plus 6 gives us 37, 37 plus 6 gives us 43. We can verify any of them by checking that the difference stays at 6.
Geometric sequences are trickier to extend because the numbers grow fast.
Let’s analyze the sequence 5, 15, 45, 135.
For this sequence the operation is multiplication, and the rule is: we multiply by 3 each time.
Extending it gives us 405, then 1,215, then 3,645.
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It’s your turn to work through some number pattern problems. Try to find the rule for each one, and then state the next three terms in the sequence.
Problem 1: 6, 11, 16, 21, 26…
Problem 2: 80, 72, 64, 56, 48…
Problem 3: 4, 12, 36, 108, 324…
Problem 4: 512, 256, 128, 64, 32…
After you’ve solved the problems, check the answers at the end of our article.

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If your child needs help understanding how number patterns work and how to identify them, we are here to help.
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If you’ve given our exercises a try, find your answers below.
Problem 1: The rule is to add 5 each time, and the next three terms are 31, 36, and 41.
Problem 2: We need to subtract 8 each time, and the next terms in this sequence are 40, 32, and 24.
Problem 3: Our rule is to multiply by 3 each time. The next three terms are 972, 2,916, and 8,748.
Problem 4: In this sequence, we divide by 2 each time, and the next three terms are 16, 8, 4.
Mathnasium of Steiner Ranch is a math-only learning center for K-12 students in Austin, TX. Trusted by over a million parents, Mathnasium uses personalized learning plans and the proprietary Mathnasium Method™ to help students catch up, keep up, and get ahead on their math journey.
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