Page 17 - Math Skill - 4
P. 17
Numbers 15
Exercise 1.6
1. Write the successor of the following numbers.
(a) 83009 (b) 359999 (c) 841260 (d) 999939
2. Write the predecessor of the following numbers.
(a) 20791 (b) 68099 (c) 782400 (d) 989412
3. Form the smallest and the greatest 5-digit numbers using the given digits.
(a) 6, 7, 2, 8, 4 (b) 1, 6, 8, 5, 3 (c) 3, 1, 4, 0, 7
(d) 2, 8, 5, 3, 6 (e) 9, 0, 4, 3, 5 (f) 7, 8, 6, 1, 5
4. Form the smallest and the greatest 6-digit numbers using the given digits.
(a) 3, 4, 7, 8, 2, 1 (b) 6, 4, 0, 2, 3, 5 (c) 1, 7, 8, 3, 4, 0
(d) 1, 0, 4, 5, 0, 7 (e) 3, 7, 8, 3, 4, 1 (f) 9, 3, 2, 1, 3, 1
Estimation
Palak went to a music concert and could see large number of people in the auditorium. When
her parents asked ‘How many people were there‘?, she said may be few thousands.
In our daily life, we come across several situations like this
where we have to guess or estimate numbers to nearest Fact-o-meter
10, 100 or 1000. While we can do the approximation or Estimation means making a
estimation roughly in day-to-day situation, there are ‘fair guess’ about numbers. It
certain rules to be followed. Let’s learn about these rules. is also called approximation.
Rounding off Numbers to the Nearest Ten
To round off a given number to the nearest ten, we find out the multiple of 10 which is nearest
to the given number.
For example, consider the numbers 22 and 29. Both the numbers lie between 20 and 30. Let us
draw a number line and locate these numbers.
20 21 22 23 24 25 26 27 28 29 30
Middle most number
On the number line, 22 is nearer to 20, so we round off 22 to 20.
On the number line, 29 is nearer to 30, so we round off 29 to 30.
Thus, the rules to round off a number to the nearest ten are as follows :
If the digit at ones place is less than 5, then replace the ones digit by 0 and keep the other
digits same as they are.
If the digit at ones place is 5 or greater than 5, then replace the ones digit by 0 and
increase the tens digit by 1.
