Decreasing number patterns, step by step
A shrinking sequence hides a rule just as a growing one does — it takes a fixed amount away each time.
The question
11, ?, 7, 5, 3
11?753
11?753
11?753
11?753
119753
- Find the rule first, from two numbers you can actually see — never from the gap.
- 7 to 5 is − 2. One pair is a guess, though — check it against another.
- 5 − 2 = 3, so the rule holds. Two pairs agreeing is what turns a guess into the rule.
- Now apply it to the gap: 11 − 2 = 9.
- Check it against the number already after the gap: 9 − 2 = 7, which is what is there. The missing number is 9.
How it works.
- 01
Find the rule first, from two numbers you can actually see — never from the gap.
- 02
7 to 5 is − 2. One pair is a guess, though — check it against another.
- 03
5 − 2 = 3, so the rule holds. Two pairs agreeing is what turns a guess into the rule.
- 04
Now apply it to the gap: 11 − 2 = 9.
- 05
Check it against the number already after the gap: 9 − 2 = 7, which is what is there. The missing number is 9.