GCSE Maths Revision Guide
Standard Form
Write very large and very small numbers using standard form (a Ć 10āæ). This free GCSE Maths module combines short explanations, worked examples, flashcard-style recall, and timed practice so students can revise the topic without creating an account.
Foundation Skills
What is Standard Form?
A number written as a Ć 10āæ, where 1 ⤠a < 10 and n is an integer.
Formula: a à 10⿠(1 ⤠a < 10)
Example: 3500 = 3.5 Ć 10³ 0.006 = 6 Ć 10ā»Ā³
Large Numbers
Count how many places the decimal point moves to the LEFT. This is your positive power.
Example: 45000 ā 4.5 Ć 10ā“
Small Numbers
Count how many places the decimal point moves to the RIGHT. This is your negative power.
Example: 0.0032 ā 3.2 Ć 10ā»Ā³
The Rule of A
The leading number MUST be between 1 and 10. 12 à 10³ is NOT in standard form.
Comparing Sizes
First compare the powers of 10. If the powers are the same, compare the leading numbers.
Example: 2 Ć 10āµ > 9 Ć 10ā“ because 10āµ is larger than 10ā“.
Higher Skills
Multiplication
Multiply the numbers and add the powers of 10.
Formula: (A Ć 10įµ) Ć (B Ć 10įµ) = (AĆB) Ć 10įµāŗįµ
Example: (3 Ć 10ā“) Ć (2 Ć 10³) = 6 Ć 10ā·
Division
Divide the numbers and subtract the powers of 10.
Formula: (A Ć 10įµ) Ć· (B Ć 10įµ) = (A/B) Ć 10įµā»įµ
Example: (8 Ć 10ā¶) Ć· (2 Ć 10²) = 4 Ć 10ā“
Addition & Subtraction
Convert both numbers to the SAME power of 10 before adding or subtracting.
Example: (3 Ć 10ā“) + (5 Ć 10³) = (30 Ć 10³) + (5 Ć 10³) = 35 Ć 10³ = 3.5 Ć 10ā“
Adjusting the Answer
If your calculation result isn't between 1 and 10, shift the decimal and adjust the power.
Example: 20 Ć 10āµ = 2 Ć 10ā¶
Negative Powers in Division
Be careful: subtracting a negative power means ADDING.
Example: 10āµ Ć· 10ā»Ā³ = 10āø
Standard Form on Calcs
Use the Ć10Ė£ or EXP button. Be careful with brackets during division!
Exam Tips
The Range Check: The number at the front (a) MUST be between 1 and 10. After every calculation, check your answer. If it's 45 Ć 10³, it is WRONG. It must be 4.5 Ć 10ā“.
Calculator "E": If your calculator screen shows "5.2 E 08", this is scientific notation for 5.2 Ć 10āø. Don't write "E" in your exam; write "Ć 10".