(a) ____ x 13 = 13 x 18
Sol: 18
Explanation: The correct answer is 18, as 18×13=13×18=234. This demonstrates the commutative property of multiplication, where changing the order of factors doesn't change the product.
(b) Whole numbers are closed under _______ and ________ operation.
Sol: Addition and Multiplication.
Explanation: Whole numbers are closed under addition and multiplication. This means that when you add or multiply any two whole numbers, the result will always be a whole number. For example, adding 2 and 3 (both whole numbers) results in 5, and multiplying 4 and 5 (both whole numbers) results in 20.
(c) Division by ______ is not defined.
Sol: Zero
Explanation: Division by zero leads to undefined behavior in mathematics. For instance, dividing any number by zero results in an undefined value because there is no number that, when multiplied by zero, equals another number.
(d) _______ is the identity for multiplication.
Sol: 1
Explanation: Division by zero leads to undefined behavior in mathematics. For instance, dividing any number by zero results in an undefined value because there is no number that, when multiplied by zero, equals another number.
(e) If ______ is added to a number, the sum will remain the same. Hence ______is called the __________ in the whole numbers.
Sol: 0, 0,Identity element for Addition.
Explanation: If 0 is added to a number, the sum will remain the same. Hence, 0 is called the identity element for addition in the whole numbers. Adding 0 to any number doesn't change its value, which demonstrates the additive identity property.
Question 1:
Answer:
Question 2:
Answer.
Ques 3: Seema got 99 marks in Math, 69 marks in English, and 91 in Science. Another student Rita got 92 marks in Math, 33 in English and 84 in Science. What are their total marks?
Ans:
Marks obtained by Seema:
Math = 99
English = 69
Science = 91
∴ Total marks obtained by Seema = 99 + 69 + 91 = 259
Marks obtained by Rita:
Math = 92
English = 33
Science = 84
So Total marks obtained by Rita = 92 + 33 + 84 = 209
Ques 4: Ramesh ordered 10 cartons of chocolates to distribute among the class. Each carton holds 20 boxes and each box has 12 chocolates. How many chocolates did Ramesh order altogether?
Ans:
2400 chocolates
Ques 5: Mukesh lives form a hostel which charges Rs 55 for Dinner and 45 for Lunch. Find the money he has to pay for seven days.
Ans:
Amount paid for lunch = 45
Amount paid for dinner = 55
Number of days = 7
Money paid by him in 7 days = 7 x (55 +45) = 700
Ques 6: Find the sum by suitable rearrangement:
(a) 837 + 208 + 363
(b) 1962 + 453 + 1538 + 647
Ans:
(a) 837 + 208 + 363 = (837 + 363) + 208
= 1200 + 208 = 1408
(b) 1962 + 453 + 1538 + 647 = (1962 + 1538) + (453 + 647)
= 3500 + 1100 = 4600
Ques 7: Find the product by suitable rearrangement:
(a) 2 x 1768 x 50
(b) 4 x 166 x 25
(c) 8 x 291 x 125
(d) 625 x 279 x 16
(e) 285 x 5 x 60
(f) 125 x 40 x 8 x 25
Ans:
(a) 2 x 1768 x 50 = 2 x 50 x 1768
= 100 x 1768 = 176800
(b) 4 x 166 x 25 = 4 x 25 x 166
= 100 x 166 = 16600
(c) 8 x 291 x 125 = 8 x 125 x 291
= 1000 x 291 = 291000
(d) 625 x 279 x 16 = 625 x 16 x 279
= 10000 x 279 = 2790000
(e) 285 x 5 x 60 = 285 x 300 = 85500
(f) 125 x 40 x 8 x 25 = 125 x 8 x 40 x 25
= 1000 x 1000 = 1000000
Ques 8: A taxi driver filled his car petrol tank with 40 litres of petrol on Monday. The next day, he filled the tank with 50 litres of petrol. If the petrol costs Rs 44 per litre, how much did he spend in all on petrol?
Ans:
Quantity of petrol filled on Monday = 40 l
Quantity of petrol filled on Tuesday = 50 l
Total quantity filled = (40 + 50) l
Cost of petrol (per l) = Rs 44
Total money spent = 44 × (40 + 50)
= 44 × 90 = Rs 3960
Ques 9: A vendor supplies 32 litres of milk to a hotel in the morning and 68 litres of milk in the evening. If the milk costs Rs 15 per litre, how much money is due to the vendor per day?
Ans:
Quantity of milk supplied in the morning = 32 l
Quantity of milk supplied in the evening = 68 l
Total of milk per litre = (32 + 68) l
Cost of milk per litre = Rs 15
Total cost per day = 15 * (32 + 68)
= 15 * 100 = Rs 1500
Ques 10: If the product of two whole numbers is zero, can we say that one or both of them will be zero? Justify through examples.
Ans:
If the product of 2 whole numbers is zero, then one of them is definitely zero.
For example, 0 * 2 = 0 and 17 * 0 = 0
If the product of 2 whole numbers is zero, then both of them may be zero.
0 * 0 = 0
However, 2 * 3 = 6
(Since numbers to be multiplied are not equal to zero, the result of the product will also be nonzero.)
Ques 11: If the product of two whole numbers is 1, can we say that one of both of them will be 1? Justify through examples.
Ans:
If the product of 2 numbers is 1, then both the numbers have to be equal to 1.
For example, 1 * 1 = 1
However, 1 * 6 = 6
Clearly, the product of two whole numbers will be 1 in the situation when both numbers to
be multiplied are 1.
Ques 12: How many whole numbers are there between 32 and 53?
Ans:
Whole numbers between 32 and 53 = 20 (53 − 32 − 1 = 20)
(33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
Ques 13: 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
Ans:
(a) 530, 503
As 530 > 503,
503 is on the left side of 530 on the number line.
(b) 370, 307
As 370 > 307,
307 is on the left side of 370 on the number line.
(c) 98765, 56789
As 98765 > 56789,
56789 is on the left side of 98765 on the number line.
(d) 9830415, 10023001
Since 98, 30, 415 < 1, 00, 23, 001,
98,30,415 is on the left side of 1,00,23,001 on the number line.
Ques 14: Solve the following using distributive property.
(a) 234 x 13 + 234 x 7
Sol: 4680
Explanation: Using the distributive property, we can factor out 234 from both terms:
234×13+234×7=234×(13+7)=234×20=4680
(b) 405 + 405 x 29
Sol: 12150
Explanation: Applying the distributive property:
405+405×29=405×(1+29)=405×30=12150
(c) 3845 x 5 x 782 + 769 x 25 x 218
Sol: 19225000
Explanation: First, we can rearrange the terms to apply the distributive property:
(769×5)×5×782+769×25×218
=769×25×782+769×25×218
=769×25×(782+218)=769×25×1000=19225000
Ques 15: Write 5 successive numbers just after 4023.
Sol: 4024, 4025, 4026, 4027, 4028
Ques 16: Write the smallest and largest 6 digit whole number.
Sol:
Smallest  100000
Largest  999999
Ques 17: Write the smallest natural and smallest whole number.
Sol: The smallest natural number is 1 because natural numbers start from 1 and go up to infinity.
The smallest whole number is 0. Whole numbers include all natural numbers along with zero.
134 videos323 docs42 tests

1. What are whole numbers? 
2. How do you add whole numbers? 
3. Can whole numbers be negative? 
4. What is the difference between whole numbers and natural numbers? 
5. How do you multiply whole numbers? 

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