Year 7 Mathematics · Unit 2

Introduction to Indices

Lesson 18 Worksheet
Name
Date
Class
Section 1, Skill Practice

Q1. Write each expression in expanded form and evaluate.

(a) 23     (b) 52     (c) 104     (d) 34     (e) 16

Q2. Write each expression using index notation.

(a) 2 × 2 × 2 × 2     (b) 7 × 7     (c) 10 × 10 × 10

(d) 4 × 4 × 4 × 4 × 4     (e) a × a × a × a

Q3. Identify the base and index in each expression.

(a) 63     (b) x5     (c) 10n     (d) (2a)4

Q4. Calculate:

(a) 20     (b) 50     (c) 1000     (d) (−3)2     (e) (−2)3

Section 2, Problem Solving

Q5. A bacteria culture doubles every hour. Starting with 100 bacteria:

(a) How many bacteria after 1 hour? 1 mark

(b) How many after 4 hours? Write your answer using index notation. 1 mark

(c) How many after n hours? 1 mark

Q6. A square has side length 3 cm. A larger square has side length 32 cm.

(a) Find the area of each square. 1 mark

(b) How many times larger is the area of the larger square? 1 mark

(c) If a square has side length 33 cm, what is its area? 1 mark

Q7. Without calculating, determine which is larger: 210 or 102? Explain your reasoning. 2 marks

Section 3, Extended Response

Q8. Investigate the pattern when powers of 2 are multiplied.

(a) Calculate 22 × 23. Write your answer as a single power of 2. 1 mark

(b) Calculate 24 × 25. Write your answer as a single power of 2. 1 mark

(c) Predict the result of 2a × 2b without calculating. 1 mark

(d) Test your prediction with 32 × 34. 1 mark

Answer Key

Q1. (a) 2×2×2=8   (b) 5×5=25   (c) 10×10×10×10=10000   (d) 3×3×3×3=81   (e) 1×1×1×1×1×1=1

Q2. (a) 24   (b) 72   (c) 103   (d) 45   (e) a4

Q3. (a) base 6, index 3   (b) base x, index 5   (c) base 10, index n   (d) base 2a, index 4

Q4. (a) 1   (b) 1   (c) 1   (d) 9   (e) −8

Q5. (a) 200   (b) 100 × 24 = 1600   (c) 100 × 2n

Q6. (a) Small: 9 cm2; Large: 81 cm2   (b) 9 times larger   (c) (33)2 = 36 = 729 cm2

Q7. 210 = 1024, 102 = 100. 210 is larger because repeated multiplication of 2 ten times produces a much larger result than 10×10.

Q8. (a) 4×8=32=25   (b) 16×32=512=29   (c) 2a+b   (d) 9×81=729=36; 2+4=6, so 32+4=36

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