Page 47 - Whole Numbers (Addition and Subtraction)

To calculate 5 726 + 2 685 you can break both numbers down, work
with the parts of the same kind, and then build the answer up:

5 726 = 5 000 + 700 + 20 + 6
2 685 = 2 000 + 600 + 80 + 5
5 000 + 2 000 = 7 000
700 + 600 = 1 300
20 + 80 = 100
6 + 5 = 11

5 726 + 2 685
= 7 000 + 1 300 + 100 + 11
Transfer 10 to 100
= 7 000 + 1 300 + 110 + 1

Transfer 100 to 1 300
= 7 000 + 1 400 + 10 + 1
Transfer 1 000 to 7 000
= 8 000 + 400 + 10 + 1
= 8 411

6. Calculate 4 758 + 2 765 in the above way, and also write your
work down in the way it is done above.

A different way to show the above thinking is to use brackets to
indicate that certain calculations are thought of separately or
done before others. The above thinking can be written like this:
5 726 + 2 685 = (5 000 + 700 + 20 + 6) + (2 000 + 600 + 80 + 5)
= (5 000 + 2 000) + (700 + 600) + (20 + 80) + (6 + 5)
= 7 000 + 1 300 + 100 + 11
= 7 000 + 1 300 + 110 + 1
= 7 000 + 1 400 + 10 + 1
= 8 000 + 400 + 10 + 1
= 8 411

7. Rewrite the work you did to calculate the answer to question 6
but this time, make use of brackets.

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