Page 31 - ICSE Math 4

Example 3: Add 4,524; 3,205 and 1,276.
Mental Maths
Solu on: Th H T O
Find:
1 1 1
4 5 2 4 (a) 2,300 + 1,299

3 2 0 5 (b) 3,000 + 2,000 + 4,000
(c) 1,299 + 2,300 + 3,000
+ 1 2 7 6
9 0 0 5

So, 4,524 + 3,205 + 1,276 = 9,005.
Addition Facts

Let’s revise the addi on facts by taking larger numbers.
• Two or more numbers can be added in
any order. Mental Maths

For example, 7,460 + 321 = 7,781 and Complete the following.
321 + 7,460 = 7,781. (a) 7,645 + 1 = _________
• Adding 0 to a number gives the same (b) 0 + 3,428 = _________

number itself. (c) 1,245 + 2,332 = _________ + 1,245
For example, 3,891 + 0 = 3,891 and (d) 1 + 1,000 + 0 = _________
0 + 7,243 = 7,243.
• Adding 1 to a number gives the next number.
For example, 2,754 + 1 = 2,755 and 1 + 3,518 = 3,519.

• A number can be wri en as the sum of two or more numbers in diff erent ways.
For example, 1,100 can be wri en as a sum of two and three numbers in the following
ways.

1,000 + 100 500 + 300 + 300

950 + 150 500 + 600
650 + 250 + 200 250 + 350 + 500

900 + 200 1,100 780 + 320 405 + 550 + 145 1,100 150 + 650 + 300

500 + 400 + 200 100 + 590 + 410
650 + 450 700 + 400

800 + 300 320 + 250 + 530

Similarly, a number can be represented as a sum of more than three numbers in

diff erent ways.

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