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GCSE Maths Revision Guide

Standard Form

Write very large and very small numbers using standard form (a Ɨ 10ⁿ). 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 Ɨ 10ⁿ, where 1 ≤ a < 10 and n is an integer.

Formula: a Ɨ 10ⁿ (1 ≤ a < 10)

Example: 3500 = 3.5 Ɨ 10³ 0.006 = 6 Ɨ 10⁻³

Large Numbers

Count how many places the decimal point moves to the LEFT. This is your positive power.

Example: 45000 → 4.5 Ɨ 10⁓

Small Numbers

Count how many places the decimal point moves to the RIGHT. This is your negative power.

Example: 0.0032 → 3.2 Ɨ 10⁻³

The Rule of A

The leading number MUST be between 1 and 10. 12 Ɨ 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 Ɨ 10⁵ > 9 Ɨ 10⁓ because 10⁵ is larger than 10⁓.

Higher Skills

Multiplication

Multiply the numbers and add the powers of 10.

Formula: (A Ɨ 10ᵃ) Ɨ (B Ɨ 10ᵇ) = (AƗB) Ɨ 10įµƒāŗįµ‡

Example: (3 Ɨ 10⁓) Ɨ (2 Ɨ 10³) = 6 Ɨ 10⁷

Division

Divide the numbers and subtract the powers of 10.

Formula: (A Ɨ 10ᵃ) Ć· (B Ɨ 10ᵇ) = (A/B) Ɨ 10įµƒā»įµ‡

Example: (8 Ɨ 10⁶) Ć· (2 Ɨ 10²) = 4 Ɨ 10⁓

Addition & Subtraction

Convert both numbers to the SAME power of 10 before adding or subtracting.

Example: (3 Ɨ 10⁓) + (5 Ɨ 10³) = (30 Ɨ 10³) + (5 Ɨ 10³) = 35 Ɨ 10³ = 3.5 Ɨ 10⁓

Adjusting the Answer

If your calculation result isn't between 1 and 10, shift the decimal and adjust the power.

Example: 20 Ɨ 10⁵ = 2 Ɨ 10⁶

Negative Powers in Division

Be careful: subtracting a negative power means ADDING.

Example: 10⁵ ÷ 10⁻³ = 10⁸

Standard Form on Calcs

Use the Ɨ10Ė£ 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 Ɨ 10³, it is WRONG. It must be 4.5 Ɨ 10⁓.

Calculator "E": If your calculator screen shows "5.2 E 08", this is scientific notation for 5.2 Ɨ 10⁸. Don't write "E" in your exam; write "Ɨ 10".

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