1.33 To perform mental calculations

Mathematics

Subtraction

Educator section

Memorandum

1.1 15

1.2 33

1.3 93

1.4 995

1.5 9 997

1.6 99 995

1.7 130

1.8 3 650

1.9 53

1.10 612 $\frac{1}{2}$

1.11 123

1.12 12

1.13 19

1.14 6

1.15 $\frac{1}{2}$

Puzzle out old code

1 286 1 335

- 539 - 934

1. 101

Leaner section

Content

Activity: to perform mental calculations [lo 1.9.1]

1. During the previous activities you have worked with very large numbers. It is equally important to be able to subtract small numbers correctly. Let us see how you will manage the following mental calculations test! Work as quickly and accurately as possible:

1.1 31 – 16 = ______________________________________________________

1.2 52 – 19 =______________________________________________________

1.3 101 – 8 =______________________________________________________

1.4 1 004 – 9 =______________________________________________________

1.5 10 003 – 6 =_____________________________________________________

1.6 100 002 – 7 =____________________________________________________

1.7 240 – 50 – 60 =__________________________________________________

1.8 4 000 – 350 =____________________________________________________

1.9 (530 × 10) ÷ 100 =________________________________________________

1.10 Halve 1 225: ____________________________________________________

1.11 Triple: ________________________________________________________

1.12 (11 × 12) - ______________________________ = 120

1.13 100 – (9 × 9) =___________________________________________________

1.14 (38 -___________________________________) ÷ 4 = 8

1.15 ____________________________________ × 850 = 425

15

Colour in: This time I have done GOOD AVERAGE POOR.

Decipher the code!

Each letter represents a digit. Can you discover the numbers?

Do you know that this kind of mathematics is called Alpha-mathematics?

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.9: We know this when the learner performs mental calculations involving:

1.9.1: addition and subtraction.