Page 94 - Ganit Kaushal

Ex 19. Find the sum of the greatest and the least six-digit numbers formed by the digits 2, 0, 4, 7, 6, 5, using
each digit only once.
Sol. Using each digit only once, the greatest six-digit number = 765420
The smallest six-digit number = 204567

Their sum = 765420 + 204567 = 969987
Ex 20. Given below are two columns – Column I and Column II. Match each item of Column I with the
corresponding item of Column II. (NCERT Exemplar)
Column I Column II

(a) The difference between two consecutive whole numbers (i) odd
(b) The product of two non-zero consecutive whole numbers (ii) 0

(c) Quotient when zero is divided by another non-zero whole number (iii) 3

(d) 2 added to three times the smallest whole number (iv) 1
(e) Smallest odd prime number (v) 2

(vi) even
Sol. (a) → (iv) (b) → (vi) (c) → (ii) (d) → (v)

(e) → (iii)
Ex 21. As per the census of 2001, the population of four states are given below. Arrange the states in ascending
and descending order of their population.
(a) Maharashtra: 96878627 (b) Andhra Pradesh: 76210007
(c) Bihar: 82998509 (d) Uttar Pradesh: 166197921
Sol. Ascending order – (b), (c), (a), (d) Descending order – (d), (a), (c), (b)
Ex 22. A mobile number consists of ten digits. The first four digits of the number are 9, 9, 8, and 7. The last
three digits are 3, 5, and 5. The remaining digits are distinct and make the mobile number the greatest
possible number. What are these digits? (NCERT Exemplar)
Sol. The available digits that have not been used are 0, 2, 4, and 6. Out of these four digits, only three
distinct digits can be selected to complete the phone number. To make the greatest possible number,
we choose 6, 4, and 2 in decreasing order. Thus, the three remaining digits are 6, 4, and 2.
Ex 23. Sheila walks 775 m to take a bus to school. She travels 2 km 225 m by bus and then walks 150 m to
reach the school. Estimate the distance from her home to school.

Sol. Total distance from Sheila’s home to school
= 775 m + 2 km 225 m + 150 m
= 775 m + 2225 m + 150 m ( 1 km = 1000 m)
≈ 800 m + 2200 m + 200 m (rounding off to nearest hundreds)
≈ 3200 m
= 3 km 200 m

Note
By rounding off to the nearest hundreds, the answer is 3 km 200 m. Rounding off to the nearest tens (do it
yourself) gives a better estimation than rounding off to the nearest hundreds.

92 Mathematics-6