Start with the slides for the quick version, then go deeper with the full study notes.
Short Study Notes in the form of Slides
Read the notes first. If the method in a worked example clicks, you're ready for the questions.
Short Study Notes β Standard Form
Start with these resources to cover the key concepts, then work through the practice questions.
Page 1 / 0
Detailed Notes
Full prose, callouts and a recap β built for A* mastery, not just a quick scan.
Take these study notes with you
Download a branded PDF β full prose, callouts, recap and memorise list for Standard Form, ready to print or save offline.
Standard Form β Cambridge IGCSE 0580 Maths Extended (2026)
Write very large and very small numbers as aΓ10n where 1β€a<10 and n is an integer. The form is non-negotiable; calculator skills and index laws do the rest.
What youβll learn
Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).
E1.4 β Use the standard form aΓ10n where n is an integer and 1β€a<10.
Convert between standard form and ordinary form.
Calculate with numbers in standard form, including addition, subtraction, multiplication, and division.
What standard form looks like
aΓ10n with a between 1 (inclusive) and 10 (exclusive). One non-zero digit before the decimal point.
Standard form writes any positive number as aΓ10n where 1β€a<10 and n is an integer.
The constraint 1β€a<10 is what makes it "standard". 20Γ104 is a correct numerical value but NOT standard form β convert to 2Γ105.
Examples in standard form.
Ordinary
Standard form
4,500
4.5Γ103
3,200,000
3.2Γ106
0.000072
7.2Γ10β5
0.6
6Γ10β1
Conversion procedure.
Big number β standard form. Move the decimal point LEFT until exactly one non-zero digit is in front. Count the moves β that's n, positive.
Small number β standard form. Move the decimal point RIGHT until exactly one non-zero digit is in front. Count the moves β that's n, negative.
Reverse direction (standard β ordinary). Move the decimal point right by n (if positive) or left by β£nβ£ (if negative).
Count the decimal-point moves to get n β left moves give a positive exponent, right moves a negative one.
Form: aΓ10n with 1β€a<10.
Big numbers: positive n.
Small numbers (less than 1): negative n.
Count decimal moves to find n.
Multiplying and dividing in standard form
Multiply the a values, then handle the powers of 10 with index laws.
Multiplication.(aΓ10m)Γ(bΓ10n)=(ab)Γ10m+n.
If ab is no longer between 1 and 10, ADJUST: shift one decimal and bump the exponent.
Worked.(3Γ104)Γ(2.5Γ106)=7.5Γ1010.
Worked needing adjustment.(4Γ105)Γ(5Γ103)=20Γ108=2Γ109.
Division.bΓ10naΓ10mβ=baβΓ10mβn.
Worked.2Γ1048Γ1012β=4Γ108.
Worked needing adjustment.6Γ1023Γ106β=0.5Γ104=5Γ103.
Handle the a-values with ordinary arithmetic and the powers of 10 with index laws β then adjust if a leaves [1, 10).
Powers and roots in standard form.
(aΓ10n)k=akΓ10nk.
aΓ10nβ β adjust n to even and use aΓ10nβ=aβΓ10n/2.
Worked.4Γ106β=2Γ103.
Worked.2.5Γ105β β odd exponent, rewrite as 25Γ104, then 25βΓ102=5Γ102.
Multiply: (aβ b)Γ10m+n.
Divide: (a/b)Γ10mβn.
Adjust if a falls outside [1,10).
For square roots, force the exponent to be even first.
Adding and subtracting in standard form
You can't add directly unless the powers of 10 match. Convert to a common power, then add.
Adding/subtracting numbers in different powers of 10 requires writing them with the SAME power first.
Worked.5.2Γ104+3.1Γ103.
Make both have Γ104:
3.1Γ103=0.31Γ104.
Sum: (5.2+0.31)Γ104=5.51Γ104.
Worked.4.8Γ10β3β2Γ10β4.
Make both have Γ10β3:
2Γ10β4=0.2Γ10β3.
Difference: (4.8β0.2)Γ10β3=4.6Γ10β3.
Tip. Choose the LARGER power of 10 as the common one β that's the one most likely to leave the answer in standard form without further adjustment.
Same power of 10 first, then add/subtract.
Choose the larger exponent as the common one.
Adjust at the end if aξ β[1,10).
Standard form on a calculator
Use the dedicated key. Typing 'Γ 10 ^ n' by hand multiplies by 10 first and then raises β wrong order.
Casio classpad / fx calculators have a dedicated key for entering Γ10n. It's labelled EXP, EE, Γ10x, or similar.
To enter 3.2Γ106: type 3.2 β EXP β 6. (NOT 3.2 Γ 10 ^ 6 β that does the right thing for this case but goes wrong for negative exponents because of operator precedence.)
To enter 4.7Γ10β5: type 4.7 β EXP β (-5).
Calculator displays usually show 3.2Γ106 as 3.2$\boxed{06}$ or 3.2E6. Always rewrite the result back to proper standard form on your answer line β examiners deduct marks for 3.2E6 written down.
Use the EXP / Γ10x key β don't type by hand.
Wrap negative exponents in brackets.
Calculator's E notation is NOT standard form.
Rewrite as aΓ10n on the answer line.
How itβs examined
Standard-form questions are guaranteed on every paper. Paper 2 typically asks to convert to/from standard form (1 mark) and to calculate (aΓ10m)Γ(bΓ10n) in standard form (2 marks). Paper 4 hides standard form inside science contexts (mass of atoms, distance to stars). Examiner reports flag two recurring slips: leaving the answer in non-standard form like 20Γ106, and writing the calculator's E notation on the answer line.
Worked examples, formulae, definitions and the mistakes examiners flag β everything you need to push from a pass to an A*.
Take this whole topic with you
Download a branded revision sheet β worked examples, formulae, definitions and common mistakes for Standard Form, ready to print or save as PDF.
Step-by-step worked examples β Standard Form
Step-by-step solutions to past-paper-style questions on standard form, written exactly the way a tutor would explain them at the board.
1Convert ordinary numbers to standard form
Coreβ’ conversion
βΌ
Question
Write in standard form: (a) 4,530,000, (b) 0.000082, (c) 73.
Step-by-step solution
Step 1
(a) Move the point so 4.53 is between 1 and 10: 6 places left β 4.53Γ106.
Step 2
(b) 8.2 is between 1 and 10: 5 places right β 8.2Γ10β5.
Step 3
(c) 7.3 between 1 and 10: 1 place left β 7.3Γ101.
Answer
(a) 4.53Γ106 (b) 8.2Γ10β5 (c) 7.3Γ101
2Convert standard form back to ordinary
Coreβ’ conversion
βΌ
Question
Write as ordinary numbers: (a) 6.04Γ104, (b) 1.27Γ10β3.
Step-by-step solution
Step 1
(a) Move 6.04 four places right β 60,400.
Step 2
(b) Move 1.27 three places left β 0.00127.
Answer
(a) 60,400 (b) 0.00127
3Multiply numbers in standard form
Extendedβ’ Adapted from 0580/42 Oct/Nov 2023 Q11β’ multiplication
βΌ
Question
Calculate (3.5Γ106)Γ(4Γ10β2) in standard form.
Step-by-step solution
Step 1
Multiply the coefficients and add the indices.
(3.5Γ4)Γ106+(β2)=14Γ104
Step 2
Adjust so coefficient is between 1 and 10.
14Γ104=1.4Γ105
Answer
1.4Γ105
Examiner tip
An answer of 14Γ104 is not in standard form. Always check that 1β€a<10.
4Add numbers in standard form
Extendedβ’ addition
βΌ
Question
Calculate (2.3Γ105)+(4.1Γ104) in standard form.
Step-by-step solution
Step 1
Equalise indices: 4.1Γ104=0.41Γ105.
Step 2
Add: 2.3+0.41=2.71.
Step 3
Result: 2.71Γ105.
Answer
2.71Γ105
5Divide numbers in standard form
Extendedβ’ Adapted from 0580/22 May/Jun 2024 Q15β’ division
βΌ
Question
Calculate 1.5Γ1036.0Γ108β, giving your answer in standard form.
Step-by-step solution
Step 1
Divide the coefficients and subtract the indices.
1.56.0βΓ108β3=4Γ105
Step 2
Coefficient 4 satisfies 1β€4<10, so the answer is already in standard form.
Answer
4Γ105
Examiner tip
The 2024 mark scheme awards a method mark for showing the subtraction of indices (108β3). Candidates who jump straight to the final number lose the method mark even when the answer is correct.
6Subtract numbers in standard form with different indices
Extendedβ’ Adapted from 0580/42 Oct/Nov 2022 Q5β’ subtraction
βΌ
Question
Calculate (5.6Γ106)β(8.4Γ105), giving your answer in standard form.
Step-by-step solution
Step 1
Equalise indices to 106: 8.4Γ105=0.84Γ106.
Step 2
Subtract: 5.6β0.84=4.76.
(5.6β0.84)Γ106=4.76Γ106
Answer
4.76Γ106
Examiner tip
The examiner report flags that candidates often subtract the coefficients without equalising the powers, producing nonsense like β2.8Γ10?. Always rewrite both numbers to share the same power of 10 first.
7Apply standard form to a population context
Extendedβ’ Adapted from 0580/42 May/Jun 2023 Q4β’ applied, context
βΌ
Question
The population of a country is 4.8Γ107. The total land area is 3.2Γ105km2. Find the population density (people per kmΒ²), giving your answer in standard form.
Step-by-step solution
Step 1
Population density =areapopulationβ.
3.2Γ1054.8Γ107β
Step 2
Compute coefficient ratio and index difference.
=3.24.8βΓ107β5=1.5Γ102
Step 3
Coefficient 1.5 is in range, so the answer is in standard form: 1.5Γ102 people per kmΒ².
Answer
1.5Γ102people/km2 (i.e. 150 people/kmΒ²)
Examiner tip
Examiners reward candidates who explicitly state the formula "population density = population Γ· area" before substituting. The 2023 mark scheme awarded a method mark for the formula even when the arithmetic was wrong.
8Order three numbers given in standard form
Extendedβ’ Adapted from 0580/22 Feb/Mar 2024 Q8β’ ordering, comparison
βΌ
Question
Place these numbers in ascending order: A=3.6Γ10β4, B=9.1Γ10β5, C=4.0Γ10β4.
Step-by-step solution
Step 1
Equalise the powers. Rewrite B=9.1Γ10β5=0.91Γ10β4.
Step 2
Now compare the coefficients with the same power: 0.91,3.6,4.0.
Step 3
Ascending: 0.91<3.6<4.0, which gives B<A<C.
Answer
B<A<C (i.e. 9.1Γ10β5<3.6Γ10β4<4.0Γ10β4).
Examiner tip
The examiner report flags that candidates routinely treat a larger coefficient as a larger number β ignoring the power. Always equalise powers first; then compare coefficients.
9Square a number in standard form
Extendedβ’ powers
βΌ
Question
Calculate (2.5Γ10β3)2, giving your answer in standard form.
Step-by-step solution
Step 1
Square the coefficient and double the index.
(2.5)2Γ102Γ(β3)=6.25Γ10β6
Step 2
Coefficient 6.25 is in range β answer is in standard form.
Answer
6.25Γ10β6
Examiner tip
Examiners reward candidates who write the index law (Γ10k)n=Γ10kn explicitly. Doubling the index (rather than squaring it: 10(β3)2=109) is a recurring error flagged in examiner reports.
10How many atoms? (Stretch context)
Challengeβ’ Adapted from 0580/42 Oct/Nov 2023 Q15β’ context, stretch, applied
βΌ
Question
The mass of one carbon atom is approximately 2.0Γ10β23g. A diamond has mass 0.4g. Estimate the number of carbon atoms in the diamond, giving your answer in standard form to 2 significant figures.
The 2023 mark scheme awards a stretch mark for the sign-handling on 10β1β(β23)=1022. Double-subtraction errors (writing 10β24) are flagged as the top mistake in the examiner report.
11Order-of-magnitude ratio between two physical quantities
Challengeβ’ Adapted from 0580/42 May/Jun 2024 Q15β’ ratio, stretch, applied
βΌ
Question
The distance from the Earth to the Sun is 1.5Γ108km. The distance from the Earth to the Moon is 3.84Γ105km. How many times further is the Sun than the Moon? Give your answer in standard form to 3 significant figures.
Step-by-step solution
Step 1
Ratio =distanceΒ toΒ MoondistanceΒ toΒ Sunβ.
3.84Γ1051.5Γ108β
Step 2
Divide coefficients and subtract indices.
=3.841.5βΓ108β5=0.390625Γ103
Step 3
Normalise: 0.390625Γ103=3.90625Γ102.
Step 4
Round to 3 s.f.: 3.91Γ102.
Answer
3.91Γ102 (the Sun is about 391 times further than the Moon)
Examiner tip
The 2024 examiner report flags that candidates often skip the standard-form normalisation, leaving the answer as 0.391Γ103. That form loses the final accuracy mark even though the value is correct β the coefficient must satisfy 1β€a<10.
Key Formulae β Standard Form
The formulae you need to memorise for standard form on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.
Standard form definition
n=aΓ10k,1β€a<10,Β kβZ
a
coefficient between 1 (inclusive) and 10 (exclusive)
k
integer power of 10
When to use
Always when expressing a number in standard form.
Multiplication rule
(aΓ10m)Γ(bΓ10n)=(ab)Γ10m+n
When to use
Multiplying two numbers in standard form. Adjust coefficient afterwards.
Division rule
bΓ10naΓ10mβ=baβΓ10mβn
When to use
Dividing two numbers in standard form.
Key Definitions and Keywords β Standard Form
Definitions to memorise and the exact keywords mark schemes credit for standard form answers β sharpened from recent examiner reports for the 2026 0580 sitting.
Standard form (scientific notation)
Examiner keyword
A number written as aΓ10k where 1β€a<10 and k is an integer.
Coefficient
The number a in aΓ10k.
Index (exponent / power)
Examiner keyword
The integer k that determines the size scale.
Common Mistakes and Misconceptions β Standard Form
The traps other students keep falling into on standard form questions β taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes β and how to avoid them.
βLeaving the coefficient outside [1,10)
0580/42 β every recent series
βΌ
Why it happens
After multiplying, students get e.g. 14Γ104 and stop without normalising.
How to avoid it
Always check 1β€a<10. Adjust by moving the decimal and changing the power.
βAdding standard-form numbers without equalising the indices
βΌ
Why it happens
Students mechanically add coefficients, ignoring that the powers differ.
How to avoid it
Match the powers first, then add coefficients.
βConfusing the direction of the decimal shift for negative exponents
βΌ
Why it happens
Negative powers of 10 make small numbers, but students still shift left.
How to avoid it
Negative exponent β small number β shift the decimal left (more zeros).
βMisreading calculator output (e.g. 4.5Eβ3) as 4.5β3
βΌ
Why it happens
The E or Γ10 symbol is small on calculator screens.
How to avoid it
Calculator 4.5Eβ3 means 4.5Γ10β3, not 4.5 to the power β3.
Practice questions
Exam-style questions with step-by-step worked solutions. Try one before checking the method.
Past paper style quiz
Get a report showing which sub-topics you've nailed and which ones still need work.
4. Exam Quiz
Assess your understanding
Attempt a past paper style quiz for this sub-topic and get instant feedback to identify your strengths and weaknesses.
Instant AI marking SchemeExaminer's feedbackAI Detailed report
Video lesson
Short walkthrough of the concepts students most often get stuck on.
Standard Form β frequently asked questions
The things students keep getting wrong in this sub-topic, answered.
Standard Form β Study Notes & Past Paper Style Questions | Cambridge IGCSE Maths 0580 Extended | Tutopiya