Chapter 1: Number System

Solution:-

False.

We know that, 0 is the whole number.

0 is no the successor of another whole number.

Solution:-

False.

For example:-

2 + 3 = 5

2 × 3 = 6

From the above example, we can say that sum of two whole numbers is not always less than their product.

Solution:-

True.

Consider the two odd numbers 2 and 5.

Then, sum = 2 + 5 = 7 it is an odd number.

Now, difference = 2 – 5 = 3 it also an odd number.

Solution:-

True.

Co-prime number is a set of numbers or integers which have only 1 as their common factor i.e. their highest common factor (HCF) will be 1. Co-prime numbers are also known as relatively prime or mutually prime numbers. It is important that there should be two numbers in order to form co-primes.

Solution:-

True.

Solution:-

False.

The HCF of two numbers is either greater than or equal to the smaller of the numbers.

Solution:-

False.

The LCM of two numbers may be equal to or greater than the larger of the numbers.

Solution:-

True.

In questions 99 to 151, fill in the blanks to make the statements true.

Solution:-

10 million = 1 crore

We know that, 1 million = 10 lakh

Then, 10 million = 10 × 10 = 100 lakh = 1,00,00,000

Therefore, 10 million = 1 crore.

(b) 10 lakh = _____ million.

Solution:-

10 lakh = 1 million.

Solution:-

1 metre = 1000millimetres

We know that, 1 metre = 100 centimetre

1 centimetre = 10 millimeter

Then, 100 cm = 10 × 100 = 1000 millimetres

(b) 1 centimetre = _____ millimetres.

Solution:-

1 centimetre = 10 millimetres.

(c) 1 kilometre = _____ millimetres.

Solution:-

1 kilometre = 10,00,000 millimetres.

We know that, 1 km = 1000 meters.

1 metre = 100 centimetre

1000 metre = 1000 × 100

= 1,00,000 centimetre

1 cm = 10 millimetres

Then, 1,00,000 centimetre = 10 × 1,00,000 = 10,00,000 millimetres