2.23 To perform mental calculations

Mathematics

Division

Educator section

Memorandum

Leaner section

Content

Activity: to perform mental calculations [lo 1.9.3]

• Let us play a game!

Play with a friend. You will each need a dice and sixteen markers. Make two boards of stiff cardboard that look like this:

• Each player now writes the following numbers on his board. You may write them where you want to.

20 ; 24 ; 32 ; 39 ; 40 ; 41 ; 48 ; 57 ; 59 ; 61 ; 66 ; 68 ; 69 ; 79 ; 86 ; 90

• When you are ready, number 1 throws the dice.
• The number that shows on the dice, is the REMAINDER that you will get when you divide a number on the board by 7 . Close that number with one of your markers. Take turns to play. The player whose board is full of markers first, is the winner.

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:

1.9.3: division with small numbers.

Test 20

1. Fill in the missing words:

1.1 Any number divided by 1 is____________________________________

1.2 When we divide a number by 2, we say we ________________________

the number. (2)

2. Complete the following flow diagrams:

(3)

3. Estimate the quotient by first rounding off the divisor to the nearest 10 and the dividend to the nearest 100:

3.1 2 468 ÷ 47 = __________________________________________

= _______________________________________(2)

3.2 3 639 ÷ 33 = __________________________________________

= _______________________________________(2)

4. Valerie had to calculate the following: 32 876 ÷ 26. She started, but could not complete the calculation. Complete the sum for her.

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_______________________________ (3)

5. Calculate the following without a calculator:

5.1 A fruit vendor buys 8 498 apples and packs them in boxes containing 35 apples each. How many boxes does he need?

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__________________________________________________________ (4)

5.2 How many rolls of chicken netting is needed to fence a camp of 1 598 m if each roll contains 45 m?

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__________________________________________________________ (4)