Approximation and Estimation

Approximation and Estimation

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The Power of Approximation and Estimation in Mathematics

Mathematics can be challenging, especially when long and tedious calculations require a quick answer. Whether faced with a non-calculator exam or trying to estimate a restaurant bill, the techniques of approximation and estimation prove to be useful. In this article, we will delve into the definitions and examples of these powerful tools.

Approximation and Estimation Defined

An approximation is a value close to the true value, but not an exact match. It is denoted by the symbol "≈". For example, we can use the approximation ≈ 3.14 for the irrational number pi, which represents the ratio of a circle's circumference to its diameter.

On the other hand, estimation involves guessing or making a rough calculation to obtain a value close to the true value. For instance, we can estimate pi by measuring the circumference and diameter of a circle and dividing them. So, if a circle has a diameter of 10 cm and a circumference of 31.4 cm, our estimation for pi would be ≈ 3.14.

Rounding Numbers

Before delving further, it is important to know how to round numbers - a crucial aspect of approximation and estimation. Rounding a number involves finding another number that is close to it but easier to work with. Let's review the process with an example.

  • Round 3728 to the nearest 10, 100, and 1000
  • Solution:
  • When rounding to the nearest 10, we look at the digits from the 10s column onwards - in this case, we have 28. Now, we ask ourselves, is 28 closer to 20 or 30? It is closer to 30, so 3728 rounds to 2730.
  • When rounding to the nearest 100, we consider the digits from the 100s column - in this case, 728. Is 728 closer to 700 or 800? It's closer to 700, so 3728 rounds to 3700.
  • Lastly, when rounding to the nearest 1000, we look at the digits from the 1000s column - in this case, 3728. Is 3728 closer to 3000 or 4000? It's closer to 4000, so we round up to 4000.

Using Approximation and Estimation - Examples

Estimating Calculations

To estimate a calculation, round all the numbers involved to a "friendly" value. For instance, if we want to multiply 72 by 91, it is easier to work with both numbers rounded to the nearest 10. This process is a form of approximation, where we say that 72 ≈ 70 and 91 ≈ 90. We can then use these numbers to estimate the multiplication result.


What is an estimate for 7.28 x 2.91?


This calculation may seem daunting without a calculator, but if we round both numbers to the nearest 10, we get 7 ≈ 10 and 2.91 ≈ 3. Thus, we can estimate the answer to be ≈ 30.

We can also calculate the percentage error between the estimated value and the actual value to see how close our estimation is to the real answer. In this case, the percentage error is only 0.026%, indicating a good estimation.

Estimating Total Cost

Sometimes, we may need to estimate the total cost of a purchase. Let's see how we can do this using approximation and estimation.


You buy 32 packets of crisps for a party, with each packet costing 21p. Estimate the total cost of the crisps.


The total cost is 32 x 21p, so we need to multiply the values to get the cost in pence. To make this easier, we can round both numbers to the nearest 10, giving us ≈ 30 x 20p = 600p. Converting this to pounds, we get a total estimate of £6.00.

Using approximation and estimation in our daily lives can save us time and effort, and with practice, we can hone our skills to make quick and accurate estimations. So, next time you are faced with a lengthy calculation, remember the power of approximation and estimation.

The Importance of Estimation and Approximation

In mathematics, the ability to estimate or approximate values plays a crucial role in simplifying calculations. While these terms may seem interchangeable, they have distinct meanings and applications. Let's explore the differences between estimation and approximation, and why these skills are essential in our everyday lives.

Solving Problems with Estimation and Approximation

To better understand the concept, let's take an example. If we know that 32 packets of crisps cost a total of £6, we can estimate that each packet costs around 19p.

The Power of Estimation and Approximation in Mathematics

Making quick and accurate calculations is essential in solving complex math problems, but it doesn't always have to be a lengthy and detailed process. Utilizing estimation and approximation techniques can give us a quick idea of the cost or value without going through tedious calculations.

We can apply these skills not only in math but also in our daily lives, such as estimating the total cost of items in a shopping basket or approximating the bill at a restaurant. Even mathematicians use these techniques in finding solutions to higher-order equations, using iterative methods to approximate the answers.

The Distinction Between Estimation and Approximation

While often used interchangeably, estimation and approximation have different meanings and uses. Estimation is an educated guess based on limited information, while approximation involves altering the true value slightly to make it more manageable. For example, instead of calculating the exact cost at 19p per packet of crisps, we can approximate it to 20p for easier calculation.

The Relevance of Estimation and Approximation in Everyday Life

Apart from being useful in mathematics, estimation and approximation are essential skills in our daily lives. Property evaluators use estimation to determine the value of a property based on various factors such as size, location, and amenities.

These skills also aid in making predictions and planning for the future. We can estimate the cost of a purchase or approximate the time needed for a task, enabling us to budget our resources and time efficiently.

Remember, every time we make an estimate or approximation, we are honing our abilities to make quick calculations, solve intricate problems, and plan effectively for the future. So, keep practicing and improving these skills!

Understanding Approximation and Estimation in Mathematics

In the world of mathematics, precision is crucial. However, there are instances where our estimations are sufficient for our calculations. This is where approximation and estimation come into play. While they may seem similar, they have distinct meanings and uses.

What is Approximation in Math?

Approximation involves using a value close to the true value to make calculations more manageable or understandable. It can include rounding numbers or using simpler values to represent complex ones. It is a valuable tool in math, making it easier and faster to solve problems.

What is Estimation in Math?

Estimation is the process of either guessing or roughly calculating a value to find an approximate answer. This is typically used when the true value is unknown, but we still want to get close to it. The key difference between approximation and estimation is that estimation is used to find the true value, while approximation is used when we already know it.

How to Estimate in Math:

  • First, round all numbers involved to an "easy" value, such as a whole number or decimal with fewer digits.
  • Then, use mental math to perform the calculation with the rounded values to get an approximate answer.

For example, to estimate the cost of two televisions priced at £133.99 each, we can round the price to £135 and then multiply it by 2, giving us an estimated cost of £270.

The Similarities and Differences Between Approximation and Estimation:

Although both approximation and estimation involve finding values close to the true value, the main difference lies in whether we know the true value or need to find it. Approximation is used when we already know the true value but need to simplify it, while estimation is used to find an answer close to the unknown true value. By understanding these concepts and when to apply them, we can enhance our problem-solving skills and make our calculations more efficient.

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