Here is a short unit of revision designed to refresh your memory before exam day and to improve your skills. The videos and resources I use here are different to the ones I used in the original unit of work. If you find you are struggling with a particular concept try going back to the original unit and looking at some of the resources there. Sometimes we just need the same information presented in a different way to be able to grasp it well.

__Objective (SL/HL)__

Be able to round to a given number of significant figures.

This is a basic skill needed for both the standard and the higher level paper and one that is well worth getting right if you are not already comfortable with rounding. It is easy to master and get a few extra points.

### Exam Tip!

Read the question carefully to see if it states how it wants you to round off your answer. If it does not say anything then give all answers to 3 significant figures.

### Rules

All non-zero digits are significant figures.

All zeros between non-zero digits are significant.

Zeros to the left of an implied decimal point are

significant.__not__Zeros to the right of an implicit decimal point

significant.__are__Leading zeros to the right of a decimal point are

significant.__not__Zero following non-zero digits to the right of the decimal point

significant.__are__

Examples -

679234 has 6 s.f. 546.39214 has 8 s.f.

7356009204 has 10 s.f. 105.034 has 6 s.f.

26 000 has 2 s.f. 26 000.0 has 6 s.f.

0.0083 has 2 s.f. 0.00830000 has 6 s.f.

### Video Recap

Revision Village - Rounding and Significant Figures.

For extra support, watch Tutorio - Rounding Numbers to Significant Figures and Decimal Places.

### Practice

__Objective (SL/HL)__

Be able to use standard form, writing large and small numbers in standard form.

Being able to work with very large and very small numbers is a key skill to master if wanting to study maths or sciences further. Writing numbers in standard form or scientific notation (both are terms you may come across) simplifies working with these numbers.

### Exam Tip!

Take an extra couple of seconds to re-read your answer making sure it is bigger or equal to one and less than 10. Also, count how far you have moved the decimal space and that you have the right power of ten written down. It is easy to miss count but really easy to spot your mistakes if you just slow down and chack your answers.

### Video Recap

Revision Village - Scientific Notation

Cognitio - What is Standard Form?

This is part 1 of 4 videos watch the next three to learn more about working with numbers in standard form.

### Practice

__Objective (SL/HL)__

Be able to calculate measurement error and percentage error.

Percentage error compares an approximate value with an exact value and then expresses this difference as a percentage. This calculation allows analysts to understand the size of the error relative to the true value. You will come across this concept in science as it relates to measurement error.

### Video Recap

Revision Village - Percentage Error

OSC - Percentage Error

### Practice

__Related Content__

In previous years of study, you will have come across lower and upper bounds. If you are not comfortable with calculating these limits then you should revise this content now.

Try these videos.

Upper and Lower Bounds - 1st Class Maths

And this one from Ace Maths.

__Exam Practice__

Depending on where you get your revision questions from:-

Revision workbook - go to it now and work through the relevant section.

__IXL__Â - Year 11 N.1-4, KK.6-10.__Revision Village__- choose your level then answer the questions starting from the easiest in the Number Skills question bank.__SaveMy Exams__Â - the number toolkit questions.__Christos Nikolaidis__- download his Numbers PDF and complete the questions.

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