Difference between revisions of "2011 AMC 8 Problems/Problem 15"

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That is one <math>1</math> followed by ten <math>0</math>'s, which is <math>\boxed{\textbf{(D)}\ 11}</math> digits.
 
That is one <math>1</math> followed by ten <math>0</math>'s, which is <math>\boxed{\textbf{(D)}\ 11}</math> digits.
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==Solution 2==
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<cmath>4^5 has four digits while 5^{10} has 7 digits. This means that </cmath>4^5 \cdot 5^{10} has a total of 7+4, 11 digits.
  
 
==See Also==
 
==See Also==
 
{{AMC8 box|year=2011|num-b=14|num-a=16}}
 
{{AMC8 box|year=2011|num-b=14|num-a=16}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 16:05, 21 November 2022

Problem

How many digits are in the product $4^5 \cdot 5^{10}$?

$\textbf{(A) } 8 \qquad\textbf{(B) } 9 \qquad\textbf{(C) } 10 \qquad\textbf{(D) } 11 \qquad\textbf{(E) } 12$

Video Solution

https://youtu.be/rQUwNC0gqdg?t=440

Solution

\[4^5 \cdot 5^{10} = 2^{10} \cdot 5^{10} = 10^{10}.\]

That is one $1$ followed by ten $0$'s, which is $\boxed{\textbf{(D)}\ 11}$ digits.

Solution 2

\[4^5 has four digits while 5^{10} has 7 digits. This means that\]4^5 \cdot 5^{10} has a total of 7+4, 11 digits.

See Also

2011 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 14
Followed by
Problem 16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AJHSME/AMC 8 Problems and Solutions

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