1. Question: The greatest number by which is 1657 and 2037 are divided to give remainders 6 and 5 respectively, is ;

    A
    127

    B
    123

    C
    235

    D
    305

    Note: solution: Required number = H.C.F. of (1657-6) & (2037-5) = H.C.F. of 1651 & 2032 =127.
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  2. Question: The greatest possible length which can be used to measure exactly the lengths 4 m 95 cm is :

    A
    15 cm

    B
    25 cm

    C
    35 cm

    D
    45 cm

    Note: solution: Required length = H.C.F. of 900 cm, 495 cm =45 cm.
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  3. Question: Three different containers contain 496 litres, 43 litres and 713 litres of mixtures of milk and water respectively. What biggest measure can measure all the different quantities exactly ?

    A
    1 litre

    B
    7 litres

    C
    31 litres

    D
    41 litres

    Note: solution: Required measurement = H.C.F. of 496,403 & 713 litres = 31 litres.
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  4. Question: The least number which is a perfect square and is divisible by each of the numbers 16, 20 and 24, is :

    A
    1600

    B
    3600

    C
    6400

    D
    1440

    Note: solution: The least number divisible by `16, 20, 24 = 1 c.m. of 16, 20, 24 =240 = 2 xx 2 xx 2 xx 2 xx 3 xx 5` To make it a perfect square, it must be multiplied by `3 xx 5`. `:.` Required number= `240 xx 3 xx 5 = 3600`.
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  5. Question: What is the least number which when divided by 8,9,12 and 15 leaves the same remainder 1 in each case ?

    A
    179

    B
    181

    C
    359

    D
    361

    Note: solution: Required number = `(1 c.m. of 8, 9, 12, 15) + 1 = 361`.
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  6. Question: What is the greatest number of three digits which when divided by 6, 9 and 12 leaves a remainder of 3 in each case ?

    A
    975

    B
    996

    C
    939

    D
    903

    Note: solution: Greatest number of 3 digits is 999. L.C.M. of `6, 9 and 12 =36`. On dividing 999 by 36, remainder obtained is 27. `:.` Greatest number of 3 digits divisible by `6, 9, 12 = (999 - 27) = 972`. `:.` Required number = `(972 + 30) = 975`.
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  7. Question: The least number of five digits which is exactly divisible by 12, 15 and 18 is :

    A
    10010

    B
    10015

    C
    10020

    D
    10080

    Note: solution: Least number of 5 digits is 10000. L.C.M. of `12, 15, 18 is 180`. On dividing 10000 by 180, the remainder is 100. `:.` Required number = `10000+(180 - 100) = 10080`.
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  8. Question: The smallest number which when diminished by 3 is divisible by 21, 28, 36 and 45 is :

    A
    423

    B
    1257

    C
    1263

    D
    1260

    Note: solution: Required number = `(1.c.m. of 21, 28, 36, 45) +3 = 1263`.
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  9. Question: The smallest number which when increased by 5 is divisible by each one of 24, 32, 36 and 54, is :

    A
    869

    B
    859

    C
    4320

    D
    427

    Note: solution: Required number = `(1.c.m. of 24, 32, 36, 54) - 5 = 859`.
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  10. Question: The least multiple of 7, which leaves a remainder of 4, when divided by 6, 9, 15 and 18, is :

    A
    74

    B
    94

    C
    184

    D
    364

    Note: solution: L.C.M. of `6, 9, 15, 18 is 90`. Let required number be `90k + 4`, which is a multiple of 7. Letast value of k for which `(90k + 4 )`is divisible by 7 is k=4. `:.` Required number = `90 xx 4 + 4 = 364`.
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