Chapter - 2- EXERCISE 2.1 Basic Geometrical Ideas (NCERT Class 6th Maths Solution)

1. Write the next three natural numbers after 10999.

Solution/Explanation:

(1) 10,999 + 1 =11,000

(2) 11,000 + 1 =11,001

(3) 11,001 + 1 =11,002

2. Write the three whole numbers occurring just before 10001.

Solution/Explanation:

10,001 – 1 =10,000
10,000 – 1 =9,999
9,999 – 1 =9,998

3. Which is the smallest whole number?

Solution/Explanation:

The whole number series is 0,1,2,3,4,5…….

0 is the smallest whole number.

W = {0,1,2,3,4…}

1 is the smallest natural number.

N = {1,2,3,4…..}

4. How many whole numbers are there between 32 and 53?

Solution/Explanation:

formula to find the whole nos between m & n is 

(m−n)−1${\displaystyle (m-n)-1}$
so applying the formula
=(53−32)−1${\displaystyle =(53-32)-1}$
=21−1=20${\displaystyle =21-1=20}$
${\displaystyle \mathrm{<br>}}$

5. Write the successor of : (a) 2440701 (b) 100199 (c) 1099999 (d) 2345670

Solution/Explanation:

successor of
(a) 2440701is=2440701+1=2440702${\displaystyle 2440701is=2440701+1=2440702}$
(b) 100199is=100199+1=100200${\displaystyle 100199is=100199+1=100200}$
(c) 1099999is1099999+1=1100000${\displaystyle 1099999is1099999+1=1100000}$
(d) 2345670is=2345670+1=2345671

6. Write the predecessor of : (a) 94 (b) 10000 (c) 208090 (d) 7654321 

Solution/Explanation:
(a)predecessor of94⇒94−1=93${\displaystyle 94\Rightarrow 94-1=93}$
(b)predecessor of10000⇒10000−1=9999${\displaystyle 10000\Rightarrow 10000-1=9999}$
(c)predecessor of208090⇒208090−1=208089${\displaystyle 208090\Rightarrow 208090-1=208089}$
(d)predecessor of7654321⇒7654321−1=7654320



7. In each of the following pairs of numbers, state which whole number is on the left of the other number on the number line. Also write them with the appropriate sign (>, <) between them. (a) 530, 503 (b) 370, 307 (c) 98765, 56789 (d) 9830415, 10023001

Solution/Explanation:  

(a) 530 > 503; So 503 appear on left side of 530 on number line.
(b) 370 > 307; so 307 appear on left side of 370 on number line.
(c) 98765 > 56789; So 56789 appear on left side of 98765 on number line.
(d) 9830415  < 10023001; So 9830415 appear on left side of 10023001 on number line.


8. Which of the following statements are true (T) and which are false (F) ? (a) Zero is the smallest natural number. (b) 400 is the predecessor of 399. (c) Zero is the smallest whole number. (d) 600 is the successor of 599. (e) All natural numbers are whole numbers. (f) All whole numbers are natural numbers. (g) The predecessor of a two digit number is never a single digit number. (h) 1 is the smallest whole number. (i) The natural number 1 has no predecessor. (j) The whole number 1 has no predecessor. (k) The whole number 13 lies between 11 and 12. (l) The whole number 0 has no predecessor. (m) The successor of a two digit number is always a two digit number.

Solution/Explanation:  

(a) false
(b) 399−1=398${\displaystyle 399-1=398}$ false
(c) true
(d) 599+1=600${\displaystyle 599+1=600}$ true
(e) 0${\displaystyle 0}$ is a whole no but not a natural number, true
(f) since 0${\displaystyle 0}$ is not a natural no, false
(g) 10−1=9${\displaystyle 10-1=9}$ false
(h) smallest whole no is 0${\displaystyle \mathrm{0 }}$false
(i) 0${\displaystyle \mathrm{0 }}$is not a natural no, true
(j) 0${\displaystyle 0}$ since 0 is a whole no , false
(k) false
(l) since −1${\displaystyle -1}$ is not a whole no, true
(m) successor of 99${\displaystyle 99}$ is 99+1=100${\displaystyle 99+1=100}$ false