Indices

  • Novemberish
    problem

    Novemberish

    Age
    14 to 16
    Challenge level
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    a) A four digit number (in base 10) aabb is a perfect square. Discuss ways of systematically finding this number. (b) Prove that 11^{10}-1 is divisible by 100.
  • A Biggy
    problem

    A Biggy

    Age
    14 to 16
    Challenge level
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    Find the smallest positive integer N such that N/2 is a perfect cube, N/3 is a perfect fifth power and N/5 is a perfect seventh power.
  • Staircase
    problem

    Staircase

    Age
    16 to 18
    Challenge level
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    Solving the equation x^3 = 3 is easy but what about solving equations with a 'staircase' of powers?
  • Multiplication Magic
    problem

    Multiplication Magic

    Age
    14 to 16
    Challenge level
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    Given any 3 digit number you can use the given digits and name another number which is divisible by 37 (e.g. given 628 you say 628371 is divisible by 37 because you know that 6+3 = 2+7 = 8+1 = 9). The question asks you to explain the trick.
  • Elevens
    problem

    Elevens

    Age
    16 to 18
    Challenge level
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    Add powers of 3 and powers of 7 and get multiples of 11.
  • More Mods
    problem

    More Mods

    Age
    14 to 16
    Challenge level
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    What is the units digit for the number 123^(456) ?
  • Growing
    problem

    Growing

    Age
    16 to 18
    Challenge level
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    Which is larger: (a) 1.000001^{1000000} or 2? (b) 100^{300} or 300! (i.e.factorial 300)
  • Power Up
    problem

    Power Up

    Age
    16 to 18
    Challenge level
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    Show without recourse to any calculating aid that 7^{1/2} + 7^{1/3} + 7^{1/4} < 7 and 4^{1/2} + 4^{1/3} + 4^{1/4} > 4 . Sketch the graph of f(x) = x^{1/2} + x^{1/3} + x^{1/4} -x
  • Remainder Hunt
    problem

    Remainder Hunt

    Age
    16 to 18
    Challenge level
    filled star filled star empty star
    What are the possible remainders when the 100-th power of an integer is divided by 125?
  • Thirty Six Exactly
    problem

    Thirty Six Exactly

    Age
    11 to 14
    Challenge level
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    The number 12 = 2^2 × 3 has 6 factors. What is the smallest natural number with exactly 36 factors?