Power Play (Exponents) | FIO

Question 11

Identify the greater number in each of the following—

(i) 434^3 or 343^4

(ii) 282^8 or 828^2

(iii) 1002100^2 or 21002^{100}

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Solution
Understand the Question
  • An exponential expression aba^b represents the base aa multiplied by itself bb times.
  • To find which number is greater, evaluate each expression numerically or compare them by expressing powers using exponent laws such as (am)n=am×n(a^m)^n = a^{m \times n}.

(i) 434^3 or 343^4

Step 1 · Evaluate and Compare 434^3 and 343^4

Evaluate 434^3

43=4×4×4=16×4=64\begin{aligned} 4^3 &= 4 \times 4 \times 4 \\ &= 16 \times 4 \\ &= 64 \end{aligned}

Evaluate 343^4

34=3×3×3×3=9×3×3=27×3=81\begin{aligned} 3^4 &= 3 \times 3 \times 3 \times 3 \\ &= 9 \times 3 \times 3 \\ &= 27 \times 3 \\ &= 81 \end{aligned}

Comparing the values 81>64    34>4381 > 64 \implies 3^4 > 4^3

Answer

(i) 343^4

(ii) 282^8 or 828^2

Step 1 · Evaluate and Compare 282^8 and 828^2

Evaluate 282^8

28=2×2×2×2×2×2×2×2=4×2×2×2×2×2×2=8×2×2×2×2×2=16×2×2×2×2=32×2×2×2=64×2×2=128×2=256\begin{aligned} 2^8 &= 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \\ &= 4 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \\ &= 8 \times 2 \times 2 \times 2 \times 2 \times 2 \\ &= 16 \times 2 \times 2 \times 2 \times 2 \\ &= 32 \times 2 \times 2 \times 2 \\ &= 64 \times 2 \times 2 \\ &= 128 \times 2 \\ &= 256 \end{aligned}

Evaluate 828^2

82=8×8=64\begin{aligned} 8^2 &= 8 \times 8 \\ &= 64 \end{aligned}

Comparing the values 256>64    28>82256 > 64 \implies 2^8 > 8^2

Answer

(ii) 282^8

(iii) 1002100^2 or 21002^{100}

Step 1 · Evaluate 1002100^2 and Compare with 21002^{100}

Evaluate 1002100^2

1002=100×100=10000\begin{aligned} 100^2 &= 100 \times 100 \\ &= 10000 \end{aligned}

Rewrite 21002^{100} using the rule (am)n=am×n(a^m)^n = a^{m \times n} 2100=(210)102^{100} = (2^{10})^{10}

Calculate 2102^{10}

210=2×2×2×2×2×2×2×2×2×2=1024\begin{aligned} 2^{10} &= 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \\ &= 1024 \end{aligned}

Substitute back into the expression 2100=(1024)102^{100} = (1024)^{10}

Since 10242=1024×1024=1048576>100001024^2 = 1024 \times 1024 = 1048576 > 10000, (1024)10(1024)^{10} is far greater than 1000010000.

Therefore 2100>10022^{100} > 100^2

Answer

(iii) 21002^{100}

Common Mistakes
  • Base ×\times Exponent Error: Incorrectly multiplying the base by the power (e.g., calculating 434^3 as 4×3=124 \times 3 = 12 instead of 4×4×4=644 \times 4 \times 4 = 64).
  • Base Size Assumption: Incorrectly assuming a larger base always yields a larger number (e.g., thinking 1002>2100100^2 > 2^{100} because 100>2100 > 2, ignoring the massive exponent 100100).

More questions in FIO

Q1

Express the following in exponential form:

(i) 6×6×6×66 \times 6 \times 6 \times 6

(ii) y×yy \times y

(iii) b×b×b×bb \times b \times b \times b

(iv) 5×5×7×7×75 \times 5 \times 7 \times 7 \times 7

(v) 2×2×a×a2 \times 2 \times a \times a

(vi) a×a×a×c×c×c×c×da \times a \times a \times c \times c \times c \times c \times d

Q2

Express each of the following as a product of powers of their prime factors in exponential form:

(i) 648

(ii) 405

(iii) 540

(iv) 3600

Q3

Write the numerical value of each of the following:

(i) 2×1032 \times 10^3

(ii) 72×237^2 \times 2^3

(iii) 3×443 \times 4^4

(iv) (3)2×(5)2(-3)^2 \times (-5)^2

(v) 32×1043^2 \times 10^4

(vi) (2)5×(10)6(-2)^5 \times (-10)^6

Q4

Find out the units digit in the value of 2224÷4322^{224} \div 4^{32}? [Hint: 4=224 = 2^2]

Q5

There are 5 bottles in a container. Every day, a new container is brought in. How many bottles would there be after 40 days?

Q6

Write the given number as the product of two or more powers in three different ways. The powers can be any integers.

(i) 64364^3 (ii) 1928192^8 (iii) 32532^{-5}

Q7

Examine each statement below and find out if it is 'Always True', 'Only Sometimes True', or 'Never True'. Explain your reasoning.

(i) Cube numbers are also square numbers.

(ii) Fourth powers are also square numbers.

(iii) The fifth power of a number is divisible by the cube of that number.

(iv) The product of two cube numbers is a cube number.

(v) q46q^{46} is both a 4th power and a 6th power (qq is a prime number).

Q8

Simplify and write these in the exponential form.

(i) 102×10510^{-2} \times 10^{-5}

(ii) 57÷545^7 \div 5^4

(iii) 97÷949^{-7} \div 9^4

(iv) (132)3(13^{-2})^{-3}

(v) m5n12(mn)9m^5 n^{12} (mn)^9

Q9

If 122=14412^2 = 144, what is

(i) (1.2)2(1.2)^2

(ii) (0.12)2(0.12)^2

(iii) (0.012)2(0.012)^2

(iv) 1202120^2

Q10

Circle the numbers that are the same—

24×3664×32610182×626242^4 \times 3^6 \qquad 6^4 \times 3^2 \qquad 6^{10} \qquad 18^2 \times 6^2 \qquad 6^{24}

Q11

Identify the greater number in each of the following—

(i) 434^3 or 343^4

(ii) 282^8 or 828^2

(iii) 1002100^2 or 21002^{100}

Q12

A dairy plans to produce 8.5 billion packets of milk in a year. They want a unique ID (identifier) code for each packet. If they choose to use the digits 0099, how many digits should the code consist of?

Q13

64 is a square number (828^2) and a cube number (434^3). Are there other numbers that are both squares and cubes? Is there a way to describe such numbers in general?

Q14

A digital locker has an alphanumeric (it can have both digits and letters) passcode of length 5. Some example codes are G89P0, 38098, BRJKW, and 003AZ. How many such codes are possible?

Q15

The worldwide population of sheep (2024) is about 10910^9, and that of goats is also about the same. What is the total population of sheep and goats?

(i) 20920^9

(ii) 101110^{11}

(iii) 101010^{10}

(iv) 101810^{18}

(v) 2×1092 \times 10^9

(vi) 109+10910^9 + 10^9

Q16

Calculate and write the answer in scientific notation:

(i) If each person in the world had 30 pieces of clothing, find the total number of pieces of clothing.

(ii) There are about 100 million bee colonies in the world. Find the number of honeybees if each colony has about 50,000 bees.

(iii) The human body has about 38 trillion bacterial cells. Find the bacterial population residing in all humans in the world.

(iv) Total time spent eating in a lifetime in seconds.

Q17

What was the date 1 arab/1 billion seconds ago?

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