Solution 1

The greatest six-digit number using the digits 2, 0, 7, 4, 9, 1 is 974210 and the smallest is 102479.

Solution 2

Rounding off Rs 5390 to the nearest thousand gives Rs 5000 and rounding off Rs 18486 gives Rs 18500. The total estimated amount which Aman needs to pay to the shopkeeper is Rs 5000 + Rs 18500 = Rs 23500.

Solution 3

Using the property of addition and subtraction, we rewrite 6250 – 999 as 6250 – 1000 + 1 = 5250 + 1 = 5251.

Solution 4

a) The HCF of two consecutive numbers is 1.

b) The smallest odd composite number is 9.

c) An example of a perfect number is 6.

d) 88 can be expressed as the sum of two odd primes, as 29 + 59.