Find a missing number when counting by 4

Find Missing Numbers: Learn

How to find a missing number in a sequence:

  • Determine if the order of numbers is ascending (getting larger in value) or descending (becoming smaller in value).
  • Find the difference between numbers that are next to each other.
  • Use the difference between numbers to find the missing number.

Example: Find the missing number: 21, 17, ?, 9

  • The order of numbers is descending (going down).
  • The difference between numbers is 21 - 17 = 4
  • Since the order is descending subtract 4 from 17. The missing number may be 13.
  • The missing number is 13 since it is 4 more than the last number 9.

Find Missing Number: Practice

Note: Look carefully at the sequence's direction.


Press the Start Button To Begin

You have 0 correct and 0 incorrect.

This is 0 percent correct.


Game Name Description Best Score
How many correct answers can you get in 60 seconds? 0
Extra time is awarded for each correct answer.
Play longer by getting more correct.
How fast can you get 20 more correct answers than wrong answers? 999