⚡ Integers: Directed Numbers, Roots & Powers

Integers are whole numbers — positive, negative, and zero. In this unit you'll master multiplying and dividing with negative signs, square and cube roots, index notation, and the correct order of operations.

Watch: signed integers orbit on a number line from −10 to +10. Positives glow pink, negatives glow blue.

✕ Sign Rules for Multiplication & Division
(+) × (+) = (+)    (−) × (−) = (+)
(+) × (−) = (−)    Same signs → Positive  |  Different signs → Negative
√ Roots
√25 = 5   because   5² = 25
∛27 = 3   because   3³ = 27
The root undoes the power
📈 Powers & Index Notation
4² = 4 × 4 = 16    2³ = 2 × 2 × 2 = 8
The index (exponent) tells you how many times to multiply
🔢 BIDMAS with Negatives
Brackets → Indices → Divide → Multiply → Add → Subtract
−3² = −(3²) = −9  but  (−3)² = +9

Sign Rules for × and ÷

Multiplication

× Positive× Negative
Positive+ Positive− Negative
Negative− Negative+ Positive

Division

÷ Positive÷ Negative
Positive+ Positive− Negative
Negative− Negative+ Positive

Memory trick: Count the negative signs.
Odd number of negatives → answer is negative.
Even number of negatives → answer is positive.

Powers, Squares & Cubes

BIDMAS with Negative Numbers

Real-World Contexts

📝 Worked Examples

Study every step before trying the exercises!

Example 1: Multiplying & Dividing Directed Numbers

Questions: (a) (−4) × (−7)   (b) 30 ÷ (−6)   (c) (−3) × 8 × (−2)

(a) Count the negative signs: 2 (even) → answer is positive.   4 × 7 = 28.   Answer: +28
(b) Count negative signs: 1 (odd) → answer is negative.   30 ÷ 6 = 5.   Answer: −5
(c) Work left to right.   (−3) × 8 = −24   (1 negative → negative)
Then −24 × (−2) = +48   (2 negatives → positive).   Answer: +48

Example 2: Square Roots and Cube Roots

Questions: (a) √144   (b) ∛125   (c) √(64 ÷ 4)

(a) What number squared gives 144?   12 × 12 = 144.   √144 = 12
(b) What number cubed gives 125?   5 × 5 = 25, then 25 × 5 = 125.   ∛125 = 5
(c) Brackets first: 64 ÷ 4 = 16.   Then √16 = 4.   Answer: 4

Example 3: Powers and Index Notation

Questions: (a) Write 3³ as a product and find its value.   (b) Evaluate (−2)⁴.   (c) Find 5² + 2³

(a) 3³ = 3 × 3 × 3 = 9 × 3 = 27
(b) (−2)⁴ = (−2)×(−2)×(−2)×(−2). Count 4 negatives (even) → positive.
    2⁴ = 16.   Answer: +16
(c) 5² = 25.   2³ = 8.   25 + 8 = 33

Example 4: BIDMAS with Negative Numbers

Questions: (a) −2 + 3 × (−4)   (b) (−10 + 4)² ÷ 3   (c) √(4² + 3²)

(a) Multiply first: 3 × (−4) = −12.   Then: −2 + (−12) = −2 − 12 = −14
(b) Brackets first: −10 + 4 = −6.   Indices: (−6)² = 36.   Then: 36 ÷ 3 = 12
(c) Indices first: 4² = 16, 3² = 9.   Brackets: 16 + 9 = 25.   Root: √25 = 5

Always ask: what's inside brackets? What are the indices? THEN multiply/divide, THEN add/subtract.

🔥 Temperature Number Line Visualizer

Click on the number line to place Temperature A (🌠️ red) and Temperature B (❄️ blue).
See the signed difference between them!

Click once for City A, click again for City B, then alternates. Drag to reposition.

How to calculate signed difference:
Difference = Temp A − Temp B   (with sign!)
e.g. A = −4°C, B = 9°C → Difference = −4 − 9 = −13°C (A is 13° colder than B)
Absolute (unsigned) gap = |−4 − 9| = 13°C

📋 Ex 1: Sign Rules Sorter

Click the correct sign (+ or ) for each multiplication or division. You get immediate feedback!

🔎 Ex 2: Roots Challenge

Type the answer for each root question, then press Check Answers.

📈 Ex 3: Powers Builder

Choose a base and an exponent to see the expanded form and result!

Base (a):

Exponent (n):

Select a base and exponent above...

🔢 Ex 4: BIDMAS with Negatives

Work out each expression using BIDMAS. Type your answer and press Check.

🌎 Ex 5: Real-World Negatives

Solve each word problem. Type your answer (just the number, e.g. −12 or 15) then press Check.

📊 Ex 6: Ordering Challenge

Click the values below in order from smallest to largest to place them in the slots.

Click a placed value to remove it. Fill all 8 slots then check!

Smallest
Largest

📝 Practice Questions

Show all your working! Use BIDMAS and sign rules carefully.

  1. Calculate: (−6) × (−3)
  2. Calculate: (−5) × 4
  3. Calculate: 24 ÷ (−8)
  4. Calculate: (−36) ÷ (−9)
  5. Find the value of 7²
  6. Find the value of 4³
  7. Find √81
  8. Find ∛8
  9. Find √121
  10. Find ∛216
  11. Evaluate: 3 + (−2) × 5
  12. Evaluate: (4 + (−6))²
  13. Evaluate: √(3² + 4²)
  14. Evaluate: −2³ + 10
  15. Evaluate: (−1) × (−2) × (−3)
  16. The temperature drops 5°C each hour. After 4 hours, write the total change as a multiplication. What is the answer?
  17. A diver is at 0 m and descends 9 m every minute for 3 minutes. Write as a multiplication. What is their depth?
  18. Find the value of (−4)²
  19. Evaluate: 20 ÷ (−4) + 3²
  20. True or False? (−3)² = −3². Explain your answer.
  1. (−6) × (−3) = +18   (two negatives → positive)
  2. (−5) × 4 = −20   (one negative → negative)
  3. 24 ÷ (−8) = −3
  4. (−36) ÷ (−9) = +4
  5. 7² = 7 × 7 = 49
  6. 4³ = 4 × 4 × 4 = 64
  7. √81 = 9   (9 × 9 = 81)
  8. ∛8 = 2   (2 × 2 × 2 = 8)
  9. √121 = 11
  10. ∛216 = 6   (6³ = 216)
  11. Multiply first: (−2) × 5 = −10. Then 3 + (−10) = −7
  12. Brackets: 4 + (−6) = −2. Indices: (−2)² = 4
  13. Indices: 3² = 9, 4² = 16. Sum = 25. √25 = 5
  14. −2³ = −(8) = −8. Then −8 + 10 = 2
  15. (−1)×(−2) = 2. Then 2 × (−3) = −6   (three negatives → negative)
  16. 4 × (−5) = −20°C total change
  17. 3 × (−9) = −27 m
  18. (−4)² = (−4) × (−4) = +16
  19. Division first: 20÷(−4) = −5. Indices: 3² = 9. Then −5 + 9 = 4
  20. False. (−3)² = (−3)×(−3) = +9. But −3² = −(3×3) = −9. The brackets make the difference!

🔥 Challenge: Integers Word Problems

Show full working for every question!

  1. The temperature in a city is −8°C on Monday. It falls by the same amount each day and reaches −20°C on Thursday (3 days later). Write a multiplication to find the daily change. What is it?
  2. A submarine is at −60 m. It divides its ascent equally over 5 minutes to reach the surface (0 m). How far does it rise each minute? Write as a division with directed numbers.
  3. A bank account has a balance of −£15. Money is deposited and withdrawn several times: +£30, then −£8, then −£4. What is the final balance? Show each step.
  4. The temperature outside is −3°C. Inside a greenhouse it is 4 times warmer (the inside temperature is 4 times greater than the outside temperature in absolute value, but positive). Write an expression and find the inside temperature. Hint: inside = 4 × |outside|.
  5. Evaluate, showing all steps:   (−2)³ + √(100 − 19) ÷ 3
  6. A number squared gives the same result whether you square the number or its negative: (n)² = (−n)². Show this is true for n = 5 and n = 7. Then explain why this always works using sign rules.
  7. Find all possible integer values of n where n² < 50. List them all, including negatives.
  8. Jamal owes his parents £3 a week for pocket money he borrowed. After 6 weeks he starts earning £5 a week and repays £3 of it each week. How many weeks after he starts earning does it take to clear the debt? Show your working.
  9. The formula for the area of a square is A = s². If s = −7 cm (a directed distance), explain why the area is still positive. Calculate the area.
  10. Evaluate: 5² − (−3)² × 2 + ∛27   using correct BIDMAS. Show each operation step by step.
  1. Change = −20 − (−8) = −12°C over 3 days. Daily change = −12 ÷ 3 = −4°C per day.
  2. Total ascent = 0 − (−60) = +60 m over 5 minutes. Distance per minute = +60 ÷ 5 = +12 m per minute. In directed terms: −60 ÷ (−5) = +12 m/min.
  3. Start: −15. After +30: −15 + 30 = +15. After −8: 15 − 8 = +7. After −4: 7 − 4 = +£3.
  4. |−3| = 3. Inside = 4 × 3 = 12°C.
  5. Indices: (−2)³ = −8. Brackets: 100 − 19 = 81. Root: √81 = 9. Division: 9 ÷ 3 = 3. Add: −8 + 3 = −5.
  6. 5² = 25 and (−5)² = (−5)×(−5) = +25 ✓.   7² = 49 and (−7)² = +49 ✓.
    Why: squaring always means two negatives, and negative × negative = positive, so the result is always positive.
  7. n² < 50 means |n| ≤ 7 (since 7²=49<50, 8²=64≥50). All integers: −7, −6, −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, 5, 6, 7 (15 values).
  8. Debt after 6 weeks: 6 × (−3) = −£18. Each week he repays £3, so debt reduces by £3 per week. Weeks to clear: 18 ÷ 3 = 6 weeks after he starts earning.
  9. Area uses s²: (−7)² = (−7) × (−7) = +49. Area is positive because squaring two negatives gives a positive. Area = 49 cm².
  10. Indices: 5²=25, (−3)²=9, ∛27=3.   Multiply: 9×2=18.   Expression: 25 − 18 + 3.   Left to right: 25−18=7, 7+3=10.