Complete a geometric number sequence
Key Notes :
⭐ Key Points
🔁 Geometric sequence is a number pattern where each number is made by multiplying or dividing the previous number by the same number.
➗➕ The same number used every time is called the rule or common ratio.
📈 Multiplying pattern
Example: 2, 4, 8, 16, ___
👉 Rule: ×2
👉 Missing number = 32
📉 Dividing pattern
Example: 81, 27, 9, ___
👉 Rule: ÷3
👉 Missing number = 3
🔍 How to find the rule
Compare the first two numbers
Check if they are multiplied or divided by the same number
Apply the same rule to find the missing term
✏️ Steps to complete a geometric sequence
Look at the given numbers
Find the multiplying or dividing rule
Use the rule to fill in the missing number(s)
⚠️ Remember
The rule stays the same throughout the sequence
Do not add or subtract in geometric sequences
🧠 Tip for students
If numbers grow fast → think multiplication
If numbers get smaller → think division
Learn with an example
1) Type the missing number in this sequence:
5, 25, _____ , 625, 3,125
First, look for a pattern. Notice how each number is 5 times the previous number:
5, 25, __, 625, 3,125
Multiply 25 by 5 to find the missing number:
25 × 5 = 125
To make the pattern complete, the number 125 must go in the blank space.
2) Type the missing number in this sequence:
2, 4, _____ , 16, 32, 64
First, look for a pattern. Notice how each number is 2 times the previous number:
2, 4, __, 16, 32, 64
Multiply 4 by 2 to find the missing number:
4 × 2 = 8
To make the pattern complete, the number 8 must go in the blank space.
3) Type the missing number in this sequence:
2, 4, 8, ____, 32, 64
First, look for a pattern. Notice how each number is 2 times the previous number:
2, 4, 8, __, 32, 64
Multiply 8 by 2 to find the missing number:
8 × 2 = 16
To make the pattern complete, the number 16 must go in the blank space.
Let’s practice!🖊️
