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Perplex
Perplex
Dashboard
Topics
Exponents & LogarithmsApproximations & ErrorSequences & SeriesCounting & BinomialsProof and Reasoning
Cartesian plane & linesQuadraticsFunction TheoryTransformations & asymptotes
2D & 3D GeometryTrig equations & identities
ProbabilityDescriptive StatisticsBivariate StatisticsDistributions & Random Variables
DifferentiationIntegration
Review VideosFormula BookletMy Progress
BlogLanding Page
Sign UpLogin
Perplex
IB Math AASL
/
Approximations & Error
/
Skills
Edit

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

IB Math AASL
/
Approximations & Error
/
Skills
Edit

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

5 Skills Available

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Rounding Numbers

2 skills
Rounding rules
SL Core 1.1

There are standardized rules for how to approximate numerical values:

  • If the digit after the one being rounded off is LESS than ​5​ (​0,1,2,3,​ or ​4​), we round down.

  • If the digit after the one being rounded off is ​5​ OR MORE (​5,6,7,8,​ or ​9​), we round up.

    ​
    1.34∣5→1.35
    ​
    ​
    1.34∣4→1.34
    ​
Significant figures
SL Core 1.1

A significant figure is any digit that is not a leading or trailing zero. To round off to a number of significant figures, count off the specified number of significant figures, then round based off of rounding rules (down if the next digit is less than ​5, up if the digit is ​5​ or more).

problem image


NOTE: Unless a question states otherwise, on IB exams, you are expected to give answers to 3 significant figures.

Scientific Notation

3 skills
Writing numbers in standard form
SL Core 1.1

Scientific notation is a useful way to write large or small numbers in a compact form. It uses powers of ​10​ to "condense" a lot of digits. Numbers written in scientific notation are of the form

​
a×10k
​

where ​1≤a<10​ and ​k∈Z.

Scientific notation is sometimes called "standard form."

Adding & subtracting numbers in scientific notation
SL Core 1.1

Let ​x=3×105,y=4×106, and suppose we want to find ​x+y.


Since the powers of ​10​ are different, we cannot simply add ​3+4. Instead, we rewrite ​y​ so it is multiplying ​105:

​
y=4×106=4×105+1=40×105
​

Now we can add:

​
x+y=3×105+40×105=43×105
​

Finally, we convert back to scientific form, since ​43>10:

​
x+y=4.3×106
​


Basically, we took the higher power of ​10​ and "split" it so that it matched the smaller power of ​10. 

Multiplying & dividing numbers in scientific notation
SL Core 1.1

We can multiply and divide numbers in scientific form as follows:

​
(3×109)×(4×105)=12×1014=1.2×1015
​
​
4×1053×109​=0.75×104=7.5×103
​

Multiplying and dividing numbers in scientific notation relies heavily on exponent rules.

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

5 Skills Available

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Rounding Numbers

2 skills
Rounding rules
SL Core 1.1

There are standardized rules for how to approximate numerical values:

  • If the digit after the one being rounded off is LESS than ​5​ (​0,1,2,3,​ or ​4​), we round down.

  • If the digit after the one being rounded off is ​5​ OR MORE (​5,6,7,8,​ or ​9​), we round up.

    ​
    1.34∣5→1.35
    ​
    ​
    1.34∣4→1.34
    ​
Significant figures
SL Core 1.1

A significant figure is any digit that is not a leading or trailing zero. To round off to a number of significant figures, count off the specified number of significant figures, then round based off of rounding rules (down if the next digit is less than ​5, up if the digit is ​5​ or more).

problem image


NOTE: Unless a question states otherwise, on IB exams, you are expected to give answers to 3 significant figures.

Scientific Notation

3 skills
Writing numbers in standard form
SL Core 1.1

Scientific notation is a useful way to write large or small numbers in a compact form. It uses powers of ​10​ to "condense" a lot of digits. Numbers written in scientific notation are of the form

​
a×10k
​

where ​1≤a<10​ and ​k∈Z.

Scientific notation is sometimes called "standard form."

Adding & subtracting numbers in scientific notation
SL Core 1.1

Let ​x=3×105,y=4×106, and suppose we want to find ​x+y.


Since the powers of ​10​ are different, we cannot simply add ​3+4. Instead, we rewrite ​y​ so it is multiplying ​105:

​
y=4×106=4×105+1=40×105
​

Now we can add:

​
x+y=3×105+40×105=43×105
​

Finally, we convert back to scientific form, since ​43>10:

​
x+y=4.3×106
​


Basically, we took the higher power of ​10​ and "split" it so that it matched the smaller power of ​10. 

Multiplying & dividing numbers in scientific notation
SL Core 1.1

We can multiply and divide numbers in scientific form as follows:

​
(3×109)×(4×105)=12×1014=1.2×1015
​
​
4×1053×109​=0.75×104=7.5×103
​

Multiplying and dividing numbers in scientific notation relies heavily on exponent rules.