Scientific notation can be very useful when estimating the answers to calculations involving very large and/or small decimal numbers.

## Example 9

A lottery winner won Â£7851 000. He put the money straight into a deposit account which earns 7.5% interest per annum (i.e. each year). If he wanted to
Author(s): The Open University

1 The new home owners from Example 4 above want to price grass seed, as well as the turf (transport only). The best buy seems to be loose seed, which says â€˜1 kilo covers 80 m2â€™. They wonder what length the side of an 80 m2
Author(s): The Open University

1 Without using your calculator, find the following:

• (a) 102

• (b) 1002

• (c) 0.12

• (d) 0.012

• (e)
Author(s): The Open University

1 Evaluate the following:

• (a) 62

• (b) 0.52

• (c) 1.52

## Answer<Author(s): The Open UniversityLicense informationRelated contentExcept for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

Up to now only those points with positive or zero coordinates have been considered. But the system can be made to cope with points involving negative coordinates, such as (âˆ’2, 3) or (âˆ’2, âˆ’3). Just as a number line can be extended to deal with negative numbers, the x-axis and y-axis can be extended to deal with negative coordinates.

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1 The frequency diagram below shows the numbers of people in different age groups in a sample of the UK population.

• (a) What is the width of each age group?

• (b) Which age group conta
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This unit shows how partial differential equations can be used to model phenomena such as waves and heat transfer. The prerequisite requirements to gain full advantage from this unit are an understanding of ordinary differential equations and basic familiarity with partial differential equations.

This unit is an adapted extract from the course Mathematical methods and models (MST209
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## Exercise 1

A vector a has magnitude |a|Â =Â 7 and direction Î¸Â =Â âˆ’70Â°. Calculate the component form of a, giving the components correct to two decimal places.

<
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After studying this unit you should:

• be able to perform basic algebraic manipulation with complex numbers;

• understand the geometric interpretation of complex numbers;

• know methods of finding the nth roots of complex numbers and the solutions of simple polynomial equations.

Author(s): The Open University

This unit is an adapted extract from the Open University course Complex analysis (M337)

This unit is devoted solely to complex numbers.

In Section 1, we define complex numbers and show you how to manipulate them, stressing the similarities with the manipulation of real numbers.

Section 2 is devoted to the geometric representation of complex numbers. You will find that
Author(s): The Open University

Journals and articles written by academics or experts are an excellent source of information. Journals are usually published monthly or quarterly, and contain a selection of articles providing details of recent research. Often they will also contain reviews of relevant books. They are usually published more quickly than books, and so are often more up to date.

To access content of journals, most publishers require a subscription. There are, however, some journals which you can freely ac
Author(s): The Open University

Keywords are significant words which define the subject you are looking for. The importance of keywords is illustrated by the fact that there is a whole industry around providing advice to companies on how to select keywords for their websites that are likely to make it to the top of results lists generated by search engines. We often choose keywords as part of an iterative process; usually if we don't hit on the right search terms straight off, most of us tweak them as we go along based on t
Author(s): The Open University

There is a variety of new approaches or terms that are interlinked, and have been prominent throughout this book. All of them have played a part in this book's journey through the scientific, political, philosophical and social implications of climate change.

Governance of climate change is about: decision making under uncertainty; understanding and representing vulnerability even when vulnerabilities are difficult to assess or unknowable; and making every aspect of human
Author(s): The Open University

By the end of this unit you should be able to:

• appreciate how chemical processes in the rest of the world affect the Arctic environment and the species inhabiting it;

• recognise the physical processes that determine atmosphere and oceanic flows in the Arctic;

• appreciate the scientific research process and the use of scientific evidence;

• use quantitative scientific evidence to examine the link between atmospheric carbon dioxide levels a
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Few people agree that individuals should take the main responsibility for tackling environmental issues. For example, in a 2007 poll of over 2000 UK citizens, 70% agreed that the government should take a lead in combating climate change, even if it means using the law to change people's behaviour. However, over 60% disagreed that there was nothing they could do to avert climate change and over half agreed that they would do more if others did more too, although 40% thought that recycling was
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Carbon dioxide (CO2) is used as the basis for the carbon footprint because it is by far the main contributor to the enhanced greenhouse effect from human activity (mainly burning fossil fuels, clearing forests and making cement). So, often only CO2 is counted in the carbon footprint. However, for a more complete measure of the carbon footprint the other human-generated greenhouse gases are converted into a CO2 equivalent (in kilograms or tonnes CO2e
Author(s): The Open University

The carbon footprint is the annual amount of greenhouse gas emissions, mainly carbon dioxide, that result from the activities of an individual or a group of people, especially their use of energy and transport and consumption of goods and services. It's measured as the mass, in kilograms or tonnes per year, either of carbon dioxide (CO2) emissions alone, or of the carbon dioxide equivalent (CO2e) effect of other greenhouse gas emissions.

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State-of-the-art models are designed to simulate the workings of the climate system (in so far as this is currently understood), and include the â€˜internalâ€™ interactions that generate short-term natural variability in the real world. They provide modellers with a means of carrying out â€˜virtualâ€™ experiments on the climate system. In the present context, an important aim of these experiments is to identify the â€˜signalâ€™ of a human influence on climate, so studies typically involve â€˜
Author(s): The Open University

Figure 36 (again adapted from the TAR) takes your thoughts on Question 11 on a stage. It gives estimates of the cumulative effect since pre-industrial times of the various climate change agents, with the contributions expressed in terms of radiative forcing. Note that the figure also includes yet another device for communicating the IPCC's confidence in a particular finding â€“ an indication of the â€˜level of scientific understandingâ€™ that accompanies each estimate. This reflects the autho
Author(s): The Open University

The notion of a link between climatic conditions and the behaviour of plants and animals (e.g. the growth of trees or coral) and the composition of natural communities or ecosystems (the type of vegetation in a given area, say) is fundamental to the use of proxy data to reconstruct past climates. Some examples of biological responses to recent climate change were included in Box 9. Here we should be wary of jumping to conclusions. Such changes involve complex living systems that can respond i
Author(s): The Open University