Indices

There are 41 NRICH Mathematical resources connected to Indices
Age of Augustus
problem

Age of augustus

Age
11 to 14
Challenge level
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The English mathematician Augustus de Morgan has given his age in algebraic terms. Can you work out when he was born?
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)
Cube Roots
problem

Cube roots

Age
16 to 18
Challenge level
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Evaluate without a calculator: (5 sqrt2 + 7)^{1/3} - (5 sqrt2 - 7)^1/3}.
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.
Pythagoras mod 5
problem

Pythagoras mod 5

Age
16 to 18
Challenge level
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Prove that for every right angled triangle which has sides with integer lengths: (1) the area of the triangle is even and (2) the length of one of the sides is divisible by 5.
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.
Powerful Factors
problem

Powerful factors

Age
16 to 18
Challenge level
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Use the fact that: x²-y² = (x-y)(x+y) and x³+y³ = (x+y) (x²-xy+y²) to find the highest power of 2 and the highest power of 3 which divide 5^{36}-1.
Big, Bigger, Biggest
problem

Big, bigger, biggest

Age
16 to 18
Challenge level
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Which is the biggest and which the smallest of $2000^{2002}, 2001^{2001} \text{and } 2002^{2000}$?
Lastly - well
problem

Lastly - well

Age
11 to 14
Challenge level
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What are the last two digits of 2^(2^2003)?
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