The least number which when divided by 4, 5 and 6 leaves remainder 1, 2 and 3 respectively, is :
[A]57
[B]59
[C]61
[D]63
57
Here 4 – 1 = 3, 5 – 2 = 3, 6 – 3 = 3
∴ The required Number = LCM of [4, 5, 6] – 3
= 60 – 3 = 57.
Hence option [A] is correct answer.
- Remainders
The smallest number which when divided by 4, 6 or 7 leaves a remainder of 2, is
- 86
- 80
- 62
- 44
Answer
Smallest number will be LCM [4,6,7] + 2.
LCM of 4, 6 and 7 is 84.
So, the smallest number leaving remainder 2 will be 86.
The correct option is A.
Solution
Step1:
Lets evaluate the LCM of 2,3,4,5 and 6.
22, 3,4,5, 621, 3,2,5, 331, 3,1,5, 351, 1,1,5, 11, 1,1,1, 1
⇒ LCM of 2,3,4,5 and 6
=2×2×3×5=60
LCM of 2,3,4,5 and 6 is 60.
Step2:
Since, the required number leaves the remainder 1 when it is divisible by 2,3,4,5,6 and no remainder when it is divisible by 7.
Therefore the required number is of the form 60x+1
⇒60x+1 is a multiple of
7
Now, lets check for
60x+1 is divisible by 7 by substituting the
natural numbers sequentially,
60[1]+1=61=[7×8]+3 is not divisible by 7.
60[2]+1=121=[7×17]+2 is not divisible by 7.
60[3]+1=181=[7×25]+6 is not divisible by 7.
60[4]+1=241=[7×34]+3 is not divisible by 7.
60[5]+1=301=[7×43]+0 is divisible by 7.
So, the least number is 301 when divided by 2,3,4,5,6 leaves a remainder 1, but when divided by 7, there will be no remainder.
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