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)
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.

Priz said:   1 decade ago
How come 35?

I need explanation.
(1)

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)

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.

111 said:   1 decade ago
Thanks Ravireja

111 said:   1 decade ago
Thanks raviteja

Nikhil said:   1 decade ago
Why it is HCF? why not LCM?

Please explain.

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.

146 said:   1 decade ago
Please give me the prime factors of 1295.

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)

Gopi krishna said:   1 decade ago
How we can find factors for such numbers?


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