What repeats if we look carefully?
By the end of this lesson
Find the next term of a simple sequence and say the rule in words (add the same number, or multiply by the same number).
Remember
- A sequence is a list with a rule.
- Ask: what do I do to get from one term to the next? Does it work every jump?
- 3, 6, 9, 12… adds 3 each time. Next is 15.
- 2, 4, 8, 16… multiplies by 2 each time. Next is 32.
- n is the position: 1st, 2nd, 3rd…
Worked examples
Cover the answer. Try the steps on paper, then open them.
Example 1 — Add-the-same
3, 6, 9, 12, …
- 6 − 3 = 3, 9 − 6 = 3, 12 − 9 = 3
- Rule: add 3
- Next: 12 + 3 = 15
Answer: 15
Check: Check every jump, not only the first.
Example 2 — Multiply-the-same
2, 4, 8, 16, …
- 4/2 = 2, 8/4 = 2, 16/8 = 2
- Rule: multiply by 2
- Next: 32
Answer: 32
Check: Adding 2 fails at the second jump.
Example 3 — Name n
In 3, 6, 9, 12 the 1st term is 3n with n=1.
- n = 1 → 3
- n = 2 → 6
- n = 4 → 12
Answer: nth term 3n
Check: Position times 3.
Common mistakes
Slip Looking at only the first jump.
Fix The same rule must fit every shown step.
Check 2nd→3rd too.
Slip Next after 2, 4, 8, 16 written as 18 (added 2).
Fix The rule is double, so 32.
Test the rule on 4→8.
Slip Thinking n is always 10.
Fix n is the seat number in the line: 1, 2, 3, …
Plug in the seat you want.
Try on paper first
Write the answer, then tap Reveal. These are not the quiz — they are warm-ups.
1. Next: 5, 10, 15, 20, …
Answer: 25
2. Next: 1, 2, 4, 8, …
Answer: 16
3. Next: 20, 17, 14, 11, …
Answer: 8
4. Rule in words for 4, 8, 12, 16?
Answer: Add 4 each time
Touch practice
8 tap / typeTap an option or type the answer. Retry any miss. Extra generated questions appear after the set if this topic allows it.
Optional picture lab
After practiceReal world
Tile patterns and cricket overs.
Connect
Loops generate sequences.
⭐ Star quiz
9 questionsFinish the touch practice first if you can. Then answer without peeking. Read every “why”.