Index notation
Objective. Write repeated multiplication using powers and evaluate integer powers.
- 1. Learn
- 2. Worked example
- 3. Practice
- 4. Feedback
- 5. Continue
Learn: the key idea
Index notation writes repeated multiplication of the same number compactly using a base and a power, such as 3⁴ meaning 3 × 3 × 3 × 3. The small raised number is the index (or exponent) and tells you how many times the base is multiplied by itself. Any non-zero number raised to the power 0 equals 1, and a power of 1 leaves the number unchanged, so 6⁰ = 1 and 6¹ = 6. To evaluate 2⁵, multiply 2 by itself five times to get 32. Index notation becomes essential later for standard form and algebraic powers.
Worked example
Write 2 × 2 × 2 × 2 × 2 in index notation and evaluate it.
- 1Count the number of twos being multiplied: five
- 2Write in index notation: 2⁵
- 3Multiply out: 2 × 2 × 2 × 2 × 2
- 4Evaluate: 2⁵ = 32
Answer: 32
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Start practisingCommon mistake. Pupils often calculate 3⁴ as 3 × 4 = 12 instead of multiplying 3 by itself four times; the correct value is 3 × 3 × 3 × 3 = 81. Always write out the repeated multiplication to avoid this.
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