Page 24 - Math Genius C3

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2. Identify the even numbers and odd numbers in the following.
2371 4628 7132 8903 3925

6000 8143 9465 3784 5828
1116 1358 2047 9999 1000
3. Write the even numbers that come between:
(a) 402 and 409 (b) 1023 and 1029 (c) 2448 and 2456

4. Write the odd numbers that come between:

(a) 111 and 119 (b) 1031 and 1038 (c) 4444 and 4450

estimatioN

Look at the following statements.
1. About 1500 people came for the annual day function.

2. Approximately 250 athletes participated in the marathon.
3. The approximate cost of a toy car is `100.

In such cases, the number gives an approximate idea which is close enough to the exact
number or amount.

This approximate value may be slightly greater or less than the actual value.
To find an approximate value is known as estimation.

This is done by rounding off the number to the nearest tens, hundreds, and so on.
rounding off a number to the nearest ten

Let us see how to round off a number to the nearest 10.

Example 1: Round off 33 to the nearest 10.

Solution: Identify the two tens between which 33 falls. The two tens are 30 and 40.
Draw a number line showing the numbers 30 to 40.

30 31 32 33 34 35 36 37 38 39 40

Using the number line, we can see that 33 is closer to 30 than to 40.

So, 33 is rounded down to 30.
Example 2: Round off 67 to the nearest 10.

Solution: Identify the two tens between which 67 falls. The two tens are 60 and 70.

Draw a number line showing the numbers 60 to 70.

60 61 62 63 64 65 66 67 68 69 70

22 Mathematics-3