MEPX
Chapter 2 of 10All chapters
  1. 1Finding the rule
  2. 2Arithmetic sequences
  3. 3Geometric sequences
  4. 4Sequences worth knowing
  5. 5Primes and factors
  6. 6Writing the nth term
  7. 7Patterns from shapes
  8. 8Recursive rules
  9. 9Patterns outside mathematics
  10. 10Solving pattern puzzles

Chapter 2 of 10

Arithmetic sequences

Adding the same amount.

The form

Each term differs from the last by a constant, so the nth term is the first term plus n minus one lots of that difference. 3, 7, 11, 15 goes up by 4 each time.

  • The graph of an arithmetic sequence is a straight line.
  • Simple interest, regular savings and evenly spaced measurements all fit.

Summing one

Pair the first with the last, the second with the second last, and every pair has the same total. That is how a young Gauss summed one to a hundred in seconds.