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

How did we get 9999? Explain it.

@ Tejas Kumblar

Nice explanation. Thanks.

Can anyone explain, Why don't we use HCF for this sum?

Why we are using lcm here instead of hcf?

Hello.

They told that greatest 4 digits no right.

So to calculate the common multiple take lcm of 15,25,40,75.

The answer will come 600 right.

Now to check the biggest 4 digits no divide the lcm by 9000, 9400, 9600, 9800.
9000/600= 15.
9400/600=47/3 i.e 15.66 not valid.
9600/600=16.
9800/600=49/3 i.e 16.33 not valid.

So the proper 4 digits greater no is 9600 which is divided by lcm which is not in fraction, so the answer is 9600.

75*8=600 lcm.

And find option divisible by 600.

How to identify whether the question given is based on LCM or HCF?

As question given greatest number then how we do LCM method ? Greatest number means HCF nah?

When greatest FOUR Digit number is to be found it means the number won't exceed 9999 so when we take 600 modulus 9999 we get remainder 399 which means that we are having 399 left after dividing 9999 with 6000 so we subtract 399 from 9999 so that remainder becomes zero and we get the greatest 4 digit number.

As the LCM of four number is 600 the number divisible by them are multiple of 600 i.e.

600
1200
1800
2400
3000
3600
4200
4800
5400
6000
6600
7200
7800
8400
9000
9600 -----> this is the greatest 4 digit number divisible.
10200.

I can't understand this problem clearly please anyone help me.