Page 45 - Start Up Mathematics_6

3. How many whole numbers have their squares equal to themselves?

4. Is division of two whole numbers always defined? Is it commutative?
5. Name a four-digit number whose predecessor is a three-digit number.

let’s evaluate
1. Write the three whole numbers occurring just after 9,998.

2. Write the three whole numbers occurring just before 20,001.
3. Write the predecessor of 1,02,999.

4. Write the successor of 76,85,949.
5. Find the sum of 2 and 7 using a number line.
6. Find the product of 3 and 6 using a number line.

7. Simplify 256 × 55 + 45 × 256 using properties of whole numbers.
8. Find the value of 1,738 × 125 – 1,738 × 25.

9. Simplify (256 ÷ 16) ÷ 4.
10. Find the least 5-digit number exactly divisible by 33.

11. By studying the pattern given below, evaluate the following:
2 × 3 3 × 4 4 × 5
1 + 2 = 1 + 2 + 3 = 1 + 2 + 3 + 4 =
2 2 2
(a) 1 + 2 + 3 + .... + 100 (b) 2 + 4 + 6 + .... + 100 (c) 30 + 31 + 32 + .... + 50

Thinking Skills

1. Does an identity element exist in addition of whole numbers? What is it? In which other
fundamental operation does an identity element exist? What is it?

2. Is the difference of two whole numbers commutative? What can you say about the absolute
values of the difference?
n
3. If d divides n completely, can we say will also divide n completely?
d
4. Which is greater, the sum of first hundred whole numbers or the product of first hundred
whole numbers?
5. If 4 is removed from the set of whole numbers, is the set closed with respect to addition?

6. If 7 is removed from the set of whole numbers, is the set closed with respect to multiplication?
7. Describe a real life situation that could be represented by the expression 8 × 4 + 6.

Values and Life Skills

1. A bus moves at a constant speed of 96 km per hour. How much distance will it cover in
14 h? Is it safe to drive above the speed limit?

2. In a canteen, a dosa costs ` 10 and a cup of tea costs ` 3. Reena had a dosa and a cup of tea
everyday for 11 days. How much money did she spend in the canteen? Is it good for your
health to eat canteen’s food regularly?

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