Page 30 - Whole Numbers (Addition and Subtraction)

2.2 Methods to add and subtract

Add by filling up multiples of 10 and 100 and 1 000

This method is useful when one number is smaller than the other
one, for example when 6 768 + 476 has to be calculated.
In this case, part of the second number is added to reach the next
multiple of 10:

6 768 + 2 → 6 770 (Step 1)
Since 476 = 2 + 474, we must still add 474.

Part of the 474 is now added on to reach the next multiple of 100:
6 768 + 2 → 6 770 + 30 → 6 800 (Step 2)

Since 474 = 30 + 444, we must still add 444.
Part of the 444 is added on to reach the next multiple of 1 000:
6 768 + 2 → 6 770 + 30 → 6 800 + 200 → 7 000 (Step 3)

Since 444 = 200 + 244, there is still 244 to be added:
6 768 + 2 → 6 770 + 30 → 6 800 + 200 → 7 000 + 244 = 7 244 (Step 4)
If you look back at the steps, you will notice that the 476 was
broken down into four parts:

2 + 30 + 200 + 244 = 476

1. (a) What part of 476 was added on to 6 768 in Step 1?
(b) What part of 476 was added on in Step 2?

(c) What part of 476 was added on in Step 3?
(d) What part of 476 was added on in Step 4?
(e) The steps are shown on this number line. What are the
numbers at the two red lines, and how far apart are they?

6 700 6 800 6 900 7 000 7 100 7 200 7 300

2. Use the filling-up method to calculate the following.
(a) 5 876 + 468 (b) 7 783 + 673
(c) 3 364 + 447 (d) 4 849 + 633

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