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She took out 3 notes of `500, 5 notes of `200, 4 notes of `100 and 1 note of `50 from her purse. So,
the total amount can be expressed as:

`2950 = `500 × 3 + `200 × 5 + `100 × 4 + `50
Seeing this, the mother asked her to give 6 notes of `500 to get back the balance.
In this case, the seller would return a `50 note to her. So, the amount can be expressed as:

`2950 = `500 × 6 – `50
Now observe the numbers written on the blackboard. What can you say about the numbers and
the lines drawn?

28,000 25,000 4,300

400
61,600 63,000

13,000
34,000 18,500
1,500

38,800 40,000 20,700

The numbers in the middle column are added in different ways to get the numbers on the sides
(25,000 + 1500 + 1500 = 28,000). The numbers in the middle can be used as many times as needed
to get the desired sum. In another example, 63,000 = 25,000 × 2 + 13,000.
Draw arrows from the middle column to the numbers on the sides to obtain the desired sums.
Example 13: Obtain the following numbers by adding and subtracting
the values given in the boxes. 300 7,000 12,000
(a) 6,500 (b) 21,400 (c) 43,000 800 1,500 50,000
Solution: (a) The number 6,500 can be obtained by adding and subtracting the given numbers
follows:

6,500 = 7,000 – 800 + 300
Also, we can find it as 6,500 = 12,000 – 7,000 + 1,500
(b) The number 21,400 can be obtained as:
21,400 = 12,000 + 7,000 + 800 + 800 + 800, i.e., 12,000 + 7,000 + 800 × 3

Also, we can find it as 12,000 + 7,000 + 1,500 × 2 – 300 × 2
(c) The number 43,000 can be obtained as:
43,000 = 50,000 – 7,000 or 12,000 × 3 + 7,000

Quick Check

Think! How can you obtain the numbers 5,900; 17,500 and 65,000 using the values given in the above example?

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