1.8 Number patterns (triangular numbers)

Mathematics

Number patterns

Educator section

Memorandum

7.

a) 1; 3; 6; 10

b).

c) Sketch 5: 15

Sketch 6: 21

10 x (10 +1) ÷ 2

= 55

25 x (25 + 1) ÷ 2

= 325

Leaner section

Content

Activity: number patterns (triangular numbers) [lo 2.3]

7. Let us also investigate TRIANGULAR NUMBERS .

• Look carefully at the following

a) Now complete the following table:

b) Draw sketches 5 and 6 and complete the table:

C. take note?

We can use the following formula to determine the number of triangles in each sketch:

E.g. Sketch 5 (S ₅ ) = 5 × (5 + 1) ÷ 2 = 15

(i) Use the formula and determine (use your pocket calculator if necessary)

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• the 10th triangular number __________________________________________
• the 25th triangular number __________________________________________

Assessment

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.3: We know this when the learner represents and uses relationships between variables in order to determine input and/or output values in a variety of ways using.