Power Play (Exponents) | A

Question 3

Tremendous in Ten!

Find a partner to play this game with. In 10 seconds, the person who writes a number or an expression, using only the digits 0-9 and arithmetic operations, that gives a number that is the larger between the two wins the round.

Below are some conditions that you may consider for different rounds.

(i) Exponents are not allowed. Only addition is allowed.

(ii) Exponents are not allowed. Only addition and multiplication are allowed.

(iii) Exponents are allowed. Only addition is allowed.

(iv) Exponents are allowed. Any arithmetic operation is allowed.

You can create your own conditions and/or involve more people to play together.

Question diagram 1Question diagram 2
Check your answer with HomiSolve it yourself, then let Homi check your steps and spot mistakes.
Solution

We will simplify each expression and then compare their values to find out which one is greater.

Step 1 — Comparing the first pair of numbers

Let us look at the first expression. It is 10,000,000,000,00010,000,000,000,000. This number has 1 followed by 13 zeros. So, we can write it as 101310^{13}.

Now, let us look at the second expression. It is 999,999×999,999999,999 \times 999,999. We can write 999,999999,999 as (1,000,0001)(1,000,000 - 1). This is (1061)(10^6 - 1). So, the expression becomes (1061)×(1061)(10^6 - 1) \times (10^6 - 1). This is the same as (1061)2(10^6 - 1)^2. We use the algebraic identity (ab)2=a22ab+b2(a-b)^2 = a^2 - 2ab + b^2. Here, aa is 10610^6 and bb is 11.

(1061)2=(106)22×106×1+12(10^6 - 1)^2 = (10^6)^2 - 2 \times 10^6 \times 1 + 1^2

=10122×106+1= 10^{12} - 2 \times 10^6 + 1

=1,000,000,000,0002,000,000+1= 1,000,000,000,000 - 2,000,000 + 1

=999,998,000,000+1= 999,998,000,000 + 1

=999,998,000,001= 999,998,000,001

Now, we compare 10,000,000,000,00010,000,000,000,000 and 999,998,000,001999,998,000,001. The first number has 14 digits. The second number has 12 digits. A number with more digits is always larger. So, 10,000,000,000,00010,000,000,000,000 is greater.

10,000,000,000,000 is greater\boxed{10,000,000,000,000 \text{ is greater}}

Diagram 1

Step 2 — Comparing the second pair of numbers

Let us look at the first expression. It is 101000+101000+101000+10100010^{1000} + 10^{1000} + 10^{1000} + 10^{1000}. This is the sum of four identical terms. We can write this as 4×1010004 \times 10^{1000}.

Now, let us look at the second expression. It is 101000000×900010^{1000000} \times 9000. We can write this as 9000×1010000009000 \times 10^{1000000}.

We need to compare 4×1010004 \times 10^{1000} and 9000×1010000009000 \times 10^{1000000}. Let us compare the exponents of 10 in both expressions. For the first expression, the exponent is 10001000. For the second expression, the exponent is 1,000,0001,000,000. We know that 1,000,0001,000,000 is much larger than 10001000. This means 10100000010^{1000000} is vastly larger than 10100010^{1000}. Specifically, 101000000=101000×1099900010^{1000000} = 10^{1000} \times 10^{999000}. So, the second expression is 9000×(101000×10999000)9000 \times (10^{1000} \times 10^{999000}). This is 9000×10999000×1010009000 \times 10^{999000} \times 10^{1000}. The first expression is 4×1010004 \times 10^{1000}. Comparing the coefficients, we have 44 versus 9000×109990009000 \times 10^{999000}. The term 9000×109990009000 \times 10^{999000} is an extremely large number. So, 9000×1010000009000 \times 10^{1000000} is much greater.

101000000×9000 is greater\boxed{10^{1000000} \times 9000 \text{ is greater}}

Diagram 2

Answer

First Comparison: 10,000,000,000,00010,000,000,000,000 is greater. Second Comparison: 101000000×900010^{1000000} \times 9000 is greater.

More questions in A

Q1

How many times can you fold it over and over?

Estu says “I heard that a sheet of paper can’t be folded more than 7 times”.

Roxie replies “What if we use a thinner paper, like a newspaper or a tissue paper?”

Try it with different types of paper and see what happens.

Q2

Think about how many combinations are possible in different contexts. Some examples are—

(i) Pincodes of places in India—The Pincode of Vidisha in Madhya Pradesh is 464001. The Pincode of Zemabawk in Mizoram is 796017.

(ii) Mobile numbers.

(iii) Vehicle registration numbers.

Try to find out how these numbers or codes are allotted/generated.

Q3

Tremendous in Ten!

Find a partner to play this game with. In 10 seconds, the person who writes a number or an expression, using only the digits 0-9 and arithmetic operations, that gives a number that is the larger between the two wins the round.

Below are some conditions that you may consider for different rounds.

(i) Exponents are not allowed. Only addition is allowed.

(ii) Exponents are not allowed. Only addition and multiplication are allowed.

(iii) Exponents are allowed. Only addition is allowed.

(iv) Exponents are allowed. Any arithmetic operation is allowed.

You can create your own conditions and/or involve more people to play together.

← Back to Power Play (Exponents)