Geometric sequences

There are 30 NRICH Mathematical resources connected to Geometric sequences
Binary Squares
problem

Binary Squares

Age
16 to 18
Challenge level
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If a number N is expressed in binary by using only 'ones,' what can you say about its square (in binary)?
Circles ad infinitum
problem

Circles ad infinitum

Age
16 to 18
Challenge level
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A circle is inscribed in an equilateral triangle. Smaller circles touch it and the sides of the triangle, the process continuing indefinitely. What is the sum of the areas of all the circles?
Converging Product
problem

Converging Product

Age
16 to 18
Challenge level
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In the limit you get the sum of an infinite geometric series. What about an infinite product (1+x)(1+x^2)(1+x^4)... ?
The Amazing Splitting Plant
problem

The Amazing Splitting Plant

Age
5 to 7
Challenge level
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Can you work out how many flowers there will be on the Amazing Splitting Plant after it has been growing for six weeks?
Magic Plant
problem

Magic Plant

Age
5 to 7
Challenge level
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On Friday the magic plant was only 2 centimetres tall. Every day it doubled its height. How tall was it on Monday?
The Great Tiling Count
problem

The Great Tiling Count

Age
7 to 11
Challenge level
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Compare the numbers of particular tiles in one or all of these three designs, inspired by the floor tiles of a church in Cambridge.
Sum the Series
article

Sum the Series

This article by Alex Goodwin, age 18 of Madras College, St Andrews describes how to find the sum of 1 + 22 + 333 + 4444 + ... to n terms.
Proof Sorter - Geometric Sequence
interactivity

Proof Sorter - Geometric Sequence

Can you correctly order the steps in the proof of the formula for the sum of the first n terms in a geometric sequence?
Pocket money
problem

Pocket money

Age
11 to 14
Challenge level
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Which of these pocket money systems would you rather have?