Don’t worry, unlock all articles / blogs on PrepInsta by just simply logging in on our website
Type atleast 3 characters
Popular Searches
Trending Pages
Notifications Mark All Read
Test Notification
Walmart is Hiring for 2024 and 2025! Batches Click here to apply!
PREPINSTA PRIME BIG BILLION SALE is live now. Go and grab the amazing offer.
asdasd
You have purchased Zoho Prime Mock Materials go to My Orders
You have purchased CTS Prime Mock Material. go to My Orders
Quants Menu9>
PREPINSTA PRIME
Get Hiring Updates right in your inbox from PrepInsta
September 14, 2023
This page consists of LCM Questions and Answers to improve your concept and speed for multiple competitive and placement exams.
To find the LCM, multiply all prime factors. But the common factors are included only once.
Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription
1. The ratio between two numbers is 13:15 and their LCM is 39780. The numbers are:
2652,3060
884, 1020
884, 1040
670, 1340
Let the numbers be 13X and 15X
Their LCM will be (13*5)X
Now (13*15)X= 39780
Therefore X= 204
Hence the numbers are (13*204, 15*204) or 2652 and 3060
Good Job! Did you know? : With $8.5 billion in their kitty, Wipro is the 4th largest Indian IT company in terms of revenue.
Oops!
2. Find the lowest number which when divided by 15, 27, 35, and 42 leaves a remainder of 9 in each case.
1890
1899
1880
1881
The lowest number which is exactly divisible by numbers 15 27 35 and 42 will be the LCM of these numbers which are mentioned below:
= 3*5*7*9*2= 1890
Therefore the required number is 1890+9= 1899
3. Find the smallest number which when increased by 8 is perfectly divisible 30 45 65 78?
1160
1150
1162
1168
The required number will be=
= {LCM of (30 45 65 78) – 8}
LCM of 30 45 65 78 =
5 30 45 65 78 3 6 9 13 78 13 2 3 13 26 2 2 3 1 2
5*3*13*2*3 = 1170
Hence the required number = 1170-8= 1162
4. Find the lowest number, which when decreased by five, is exactly divided by 20 28 35 105?
420
425
430
440
Clearly the required which when reduced by 5 will be LCM of 20 28 35 105
Hence the required number = {LCM of 20 28 35 105) + 5}
LCM of 20 28 35 105 =
= 5*7*4*3 = 420
420+5= 425
5. Find the lowest number which when divided by 35 45 55 leaves the remainders 18 28 38 respectively?
3440
3448
3445
3450
Here the difference between the divisor and its corresponding remainder = 17 (35-18= 17 similarly 45-28= 17 and 55-38= 17)
Therefore the required number will be = { (LCM of 35 45 55) – 17}
= (5*7*9*11) – 17= 3465-17
= 3448
Therefore option B is the correct one.
6. Five bells begin to toll together and toll respectively at intervals of 6, 7, 8, 9, and 12 seconds. How many seconds will they toll together again?
72 sec
612 sec
504 sec
318 sec
The number of times the bells will toll together = LCM of 6, 7, 8, 9, and 12 = 504
7. If the two numbers are in the given ratio, which is 4:5 and their H.C.F is 40, find their L.C.M.
37
45
40
None of the above
Let the number be 4y and 5y
L.C.M = 20 y
20y = 40
Y = 2
So the numbers will be 4*2 = 8
5*2 = 10
L.C.M of 8 and 10 is 40
8. The given ratio of two numbers is 3:2. If the L.C.M of them is 30, then calculate their sum.
34
50
55
Let the given numbers be = 3y and 2y
LCM = 6Y
6Y = 30
Y = 5
The two numbers will be 3*5 = 15 and 2*5 = 10
Their sum will be = 10+15 = 25
9. Find the LCM of two numbers whose product is 2025 and their HCF is 15?
30375
2040
135
2010
LCM=\frac{product of two numbers}{HCF} = \frac{2025}{15}=135
10. The product of two-digit numbers is 2160, and their GCM is 12. The numbers are:
12,180
72, 30
36, 60
96, 25
Let the numbers be 12a and 12b
Then 12a*12b= 2160 or ab=15
Therefore the values of co-primes a and b are (1,15) and (3,5)
Hence the two-digit numbers are (3*12, 5*12), i.e. 36, 60
Please login to report
Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others