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6th Grade > Mathematics

PLAYING WITH NUMBERS MCQs

Total Questions : 100 | Page 2 of 10 pages
Question 11. What is the greatest four digit number which is divisible by 15, 25, 40 and 75? [4 MARKS]
 Discuss Question

:
Steps: 3 Marks
Answer: 1 Mark
The greatest number of 4-digits is 9999.
The prime factors of the given numbers are:
15=3×5
25=5×5
40=2×2×2×5
75=3×5×5

The maximum number of times the prime factor 2 occurs is 3.
The maximum number of times the prime factor 3 occurs is 1.
The maximum number of times the prime factor 5 occurs is 2.
The LCM of the given numbers=2×2×2×3×5×5
L.C.M. of 15, 25, 40 and 75 is 600.
On dividing 9999 by 600, the remainder is 399.
Required number (9999 - 399) = 9600.
Question 12. Oshin has 36 chocolates. Among how many possible sets of children can she distribute the chocolate so that each child gets an equal number of chocolates without breaking the chocolates? [2 MARKS]
 Discuss Question

:
Steps: 1 Mark
Answer: 1 Mark
Oshin can distribute the chocolates by finding the factors of 36: Each of the factors will divide the chocolates in an equal number of parts, So each child will get an equal number of chocolates.
We can find the factors of 36 in the following way:

36=1×36
36=2×18
36=3×12
36=4×9
36=6×6
Stop here, because both the factors (6) are same.
Thus, the factors are 1, 2, 3, 4, 6, 9, 12, 18 and 36. So she can distribute in 9 possible sets, depending on how many children form one set.
Question 13. H.C.F of 45, 81 and 27 is _____.
  1.    45
  2.    27
  3.    9
  4.    1
 Discuss Question
Answer: Option C. -> 9
:
C
Factors of 45 = 1, 3, 5, 9, 15, 45
Factors of 81= 1, 3,9, 27, 81
Factors of 27= 1, 3, 9, 27
The common factors of 45, 81 and27 are 1, 3 and9.
So, the H.C.F of 45, 81 and27 = 9.
Question 14. The prime factors of a number is given as 3 × × 11 × 101. Which of the following is correct about the number?
  1.    It is an even number.
  2.    It is the smallest 4 digit odd number.
  3.    The number is 10000.
  4.    It is the greatest 4 digit number.
 Discuss Question
Answer: Option D. -> It is the greatest 4 digit number.
:
D
On simplification of the given expression, we get that
3
×3×11×101 = 9999.
We can observe that it is the greatest 4 digit number.
Also, we can see that this is an odd number.
Question 15. L.C.M. of 1 and 90 is __.
  1.    90
  2.    360
  3.    45
  4.    1
 Discuss Question
Answer: Option A. -> 90
:
A
Multiples of 90 will be 90, 180, ...... and
Multiples of 1 will be 1, 2, 3...90 and so on.
From the above, we can say that, the least common multiple of 1 and 90 will be90.
The L.C.M. of 1 and any other number, say 'x' is always 'x'.
Question 16. The H.C.F of two co-prime numbers is
  1.    4
  2.    1
  3.    2
  4.    3
 Discuss Question
Answer: Option B. -> 1
:
B
Numbers, which do not have any common factor between them other than one, are calledco-prime numbers.
For example, 3 and 7 are co-prime numbers. Theyonly have 1 as a common factor.
Question 17. The LCM of  18, 24 & 32 is _______.
  1.    288
  2.    32
  3.    24
  4.    432
 Discuss Question
Answer: Option A. -> 288
:
A
LCM of 18, 24 and 32 is
The LCM Of  18, 24 & 32 Is _______.
So, LCM = 2×2×2×2×2×3×3
= 288
Question 18. A farmer has 3 storage units for rice. Each storage unit has the same capacity. Rice is available to the farmer in bags of 80 kg, 85 kg and 90 kg. Find the minimum storage capacity of each of the storage unit considering that he has to take rice in bags of 80 kg, 85 kg and 90 kg only.
  1.    14220 kg
  2.    12240 kg
  3.    12440 kg
  4.    14422 kg
 Discuss Question
Answer: Option B. -> 12240 kg
:
B
The capacity of each storage unit should be same as well as minimum. The required minimum capacity should be the LCM of 80 kg, 85 kg & 90 kg.
A Farmer Has 3 Storage Units For Rice. Each Storage Unit Has...
2×2×2×2×5×9×17=12240
LCM of 80,85,90=12240
Question 19. Find the least number which when divided by 32, 64 & 128 leaves the remainder of 8.
  1.    1024
  2.    1034
  3.    136
  4.    128
 Discuss Question
Answer: Option C. -> 136
:
C
The smallest number that is divisible by32, 64, 128 is the LCM of32, 64, 128.
LCM of 32, 64, 128 =

Find The Least Number Which When Divided By 32, 64 & 128...
= 2×2×2×2×2×2×2
=128
When 128 is divided by 32, 64 & 128 there is no remainder. So, to get remainder 8 when divided by32, 64 & 128, 8 is to be added to 128i.e., 128+8 = 136
Question 20. LCM of two numbers is 12 and HCF of same two numbers is 2. If one of the numbers is 6 then the other number is _____.
  1.    6
  2.    4
  3.    12
  4.    14
 Discuss Question
Answer: Option B. -> 4
:
B
It is given that LCM = 12;HCF=2
Product of 2 numbers = HCF× LCM of the respective numbers
6 ×the other number = 12 ×2
6 ×the other number = 24
the other number = 246= 4
Hence, theother number = 4

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