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Aptitude - Problems on H.C.F and L.C.M - Discussion

Discussion Forum : Problems on H.C.F and L.C.M - General Questions (Q.No. 21)
Problems on H.C.F and L.C.M
21.
The greatest possible length which can be used to measure exactly the lengths 7 m, 3 m 85 cm, 12 m 95 cm is:
15 cm
25 cm
35 cm
42 cm
Answer: Option
Explanation:

Required length = H.C.F. of 700 cm, 385 cm and 1295 cm = 35 cm.

Discussion:
42 comments Page 1 of 5.
Sindhuroyal said:   9 years ago
Firstly we have to find two number which is low among three numbers. So we have to take 385,700., in this two numbers 700 is divided by 385.
385)700(1
    385
   _______
   315)385(1
       315
        _____
          70)315(4
             280
            _______
            35)70(2
               70
             _____
               0
The above two numbers is divided till we get remainder is 0. Then last number 35 is need to taken. We have other number which is 1295.
35)1295(37
   105
   _____
    245
    245
   _____
     0 
   _____
So that, 35 is answer guys.
Archit said:   8 years ago
It is very simple.

Just check the options , if any option is not divisible by any length then you can rule out that option.

Suppose 15 =3*5 where 3 is not divisible by 700 so it's not the right option.
Now 25 is not divisible by 385 so it is also ruled out,
Now 35 =7*5 which can be divided by all,
And last 42 (is even will give even multiple) which is also not divisible by 385 and you don't even have to check for the last one.
(3)
Raviteja said:   1 decade ago
Required length = H.C.F. of 700 cm, 385 cm and 1295 cm.
385)700(1
    385
    ---
    315)385(1
        315
        ---
        70)315(4
           280
           ---
           35)70(2
              70
              --
               x

35)1295(37
   1295
   ----
    X
   ----
i.e., H.C.F. of 700 cm, 385 cm and 1295 cm = 35 cm.
Aparna said:   1 decade ago
Don't worry its very easy

Whenever in the question,words like greatest or measurement or length comes,it is an HCF question
look at the options
the answers are in cm,so convert in cm all the values

e.g:
3m 85cm

1m=100cm
3m=?

we get,300cm
just add 85 in this,but don't do mutiplication
i:e
300+85=385

similarly,do with other nos.
and further find its HCF
(1)
NareshBora said:   1 decade ago
Easy process to find HCF is

7m = 7*100 = 700cm.

3m85cm = 3*100+85 = 385cm.
12m95cm = 1200+95 = 1295cm.

Given lengths in cm are 700, 385, 1295

Now 700-385 = 315.

1295-385 = 910.
1295-700 = 595.

Factors for 315 = 7*5*3*3.

910 = 7*5*2*13.
595 = 7*5*17.

Common Highest factor is 7*5 = 35.

So, answer is 35.
(13)
Tessa said:   9 years ago
We need a length which can be used to measure the three given Lengths.

So it should be a common factor of all three numbers nd it should be the greatest also. So it's clearly highest common factor or HCF.
(1)
NKC said:   8 years ago
In this question, we need a length that can measure all the lenths but the length of the required scale is shortest that can esasily multiples of the given lengths.
Ajay said:   7 months ago
1 meter =100cm.
7 meter become 700 cm,
3m 85cm become 385cm,
12m 95cm became 1295cm,
HCF of 700,385,1295 is 35,
So, 35 is the required answer.
145 said:   1 decade ago
As we need to find out greatest possible length as mentioned in the queue. We need to find out HCF and not LCM.
Abhishek chaudhary said:   9 years ago
Please tell me one thing. When we have to take LCM and HCF?

I am confused about this.
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