## An exercise on rounding values in a calculation to find an approximate estimate of the answer.

##### RoundingLevel 1Level 2Level 3Level 4BoundsExam-StyleDescriptionHelpMore ...

This is level 3: determine whether an approximation is a over-estimate or an under-estimate if each of the numbers are rounded to one significant figure. You will be awarded a trophy if you get at least 9 correct and you do this activity online.

 $$93 \times 21$$ under-estimate :: over-estimate $$29 + 76$$ under-estimate :: over-estimate $$74 - 29$$ under-estimate :: over-estimate $$99 - 54$$ under-estimate :: over-estimate $$68 \div 21$$ under-estimate :: over-estimate $$80.3 \div 4.6$$ under-estimate :: over-estimate $$\frac{62 \times 84}{1.85}$$ under-estimate :: over-estimate $$\frac{36 + 18}{4.37}$$ under-estimate :: over-estimate $$\frac{13 \times 9.25}{0.56}$$ under-estimate :: over-estimate $$\frac{59.1 - 7.12}{7.37 + 3.34}$$ under-estimate :: over-estimate $$\frac{703 \times 0.546}{0.096}$$ under-estimate :: over-estimate $$\frac{41^2}{9.9} - \frac{35 - 9.3}{0.14}$$ under-estimate :: over-estimate
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This is Rough Answers level 3. You can also try:
Level 1 Level 2 Level 4

## Instructions

Try your best to answer the questions above. Type your answers into the boxes provided leaving no spaces. As you work through the exercise regularly click the "check" button. If you have any wrong answers, do your best to do corrections but if there is anything you don't understand, please ask your teacher for help.

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#### Connect 4 Factors

A mathematical version of the popular Connect 4 game based on getting four numbers with a common factor in a line. Fun for one, two or a whole class of pupils.

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## Go Maths

Learning and understanding Mathematics, at every level, requires learner engagement. Mathematics is not a spectator sport. Sometimes traditional teaching fails to actively involve students. One way to address the problem is through the use of interactive activities and this web site provides many of those. The Go Maths page is an alphabetical list of free activities designed for students in Secondary/High school.

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## Teachers

If you found this activity useful don't forget to record it in your scheme of work or learning management system. The short URL, ready to be copied and pasted, is as follows:

Jen, Australia

Saturday, June 1, 2019

"I just tried level one. It looks like a great way to reinforce significant figures to students, through mental estimates! However, the question says give answers to one significant figure - and I just got most of the questions "wrong", as your answers are mostly to 2 significant figures."

Transum,

Sunday, June 2, 2019

"Thanks very much for your feedback Jen. The instructions ask for the numbers in the questions to be rounded to one significant figure; not the answers. The answers should be given exact after the pre-calculation rounding has taken place. Once again thanks for the feedback, much appreciated."

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© Transum Mathematics :: This activity can be found online at:
www.transum.org/Maths/Exercise/Approximating/Default.asp?Level=3

## Description of Levels

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Rounding - Before doing these exercises you will need to know how to round numbers to one significant figure.

Level 1 - Round the numbers in a basic calculation to one significant figure to obtain an approximate answer

Level 2 - Round the numbers to one significant figure to obtain an approximate answer to calculations including decimals and fractions

Level 3 - Determine whether an approximation is a over-estimate or an under-estimate if each of the numbers are rounded to one significant figure

Level 4 - Real life problems and puzzles

Bounds - Determine the upper and lower bounds when rounding or truncating quantities used in calculations.

Exam Style Questions - A collection of problems in the style of GCSE or IB/A-level exam paper questions (worked solutions are available for Transum subscribers).

Breathe Easily - A real-life question that can be (roughly) answered by making some approximations.

Fermi Problem - Unleash your approximating skills to estimate something quite unknown in this Advanced Starter.

More on this topic including lesson Starters, visual aids, investigations and self-marking exercises.

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## Curriculum Reference

See the National Curriculum page for links to related online activities and resources.

## Example

The video above is from the maths520 channel.

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Answers to this exercise are available lower down this page when you are logged in to your Transum account. If you don’t yet have a Transum subscription one can be very quickly set up if you are a teacher, tutor or parent.

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