1.13 To perform mental calculations

Mathematics

Number concept

Educator section

Memorandum

1.1 8

1.2 12

1.3 775

1.4 2 700

1.5 * +7

1.6 11

1.7 9 rem 3

1.8 9 000

1.9 6 248

1.10 504

1.11 350

1.12 200

1.13 45

1.14 8

1.15 6 rem 5

Leaner section

Content

Activity: to perform mental calculations [lo 1.9.1, lo 1.9.2]

1. It is time to see whether you are able to improve your skill in mental calculation. Without using a pocket calculator, work as quickly and accurately as possible:

1.1 ________ x 9 = 72 1.9

1.2 ________ x 8 = 96

1.3 5 000 − 4 225 = ________

1.4 2 575 + 125 = ________

1.5 (7 x ________ + 7 = 70

1.6 (5 x 9) − ________ = 34

1.7 84 ¸ 9 = ________

• Round off to the nearest 1 000: 9 450: ________
• Double: 3 124: ________

1.10 Halve 1 008: ________

1.11 250 + 25 + 75 = ________

1.12 (9 x 12) + 92 = ________

1.13 (12 x 12) − ________ = 99

1.14 (42 + ________) x 100 = 5 000

1.15 53 ¸ 8 = ________

I got _______________________________________ out of the 15 correct!

Colour the appropriate space: I have:

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;

1.9.2: multiplication of whole numbers to at least 12 x 12.