Difference between revisions of "Mock AIME 5 Pre 2005 Problems/Problem 12"

m (solution)
 
(Solution)
 
(4 intermediate revisions by 3 users not shown)
Line 1: Line 1:
 
== Problem ==
 
== Problem ==
Let <math>m = 101^4 + 256</math>. Find the sum of digits of <math>m</math>.  
+
Let <math>m = 101^4 + 256</math>. Find the sum of the digits of <math>m</math>.
  
 
== Solution ==
 
== Solution ==
By the [[binomial theorem]], <math>101^4 + 256 = 104060401 + 256 = 104060657</math>, and <math>s(m) = \boxed{029}</math>.
+
By the [[binomial theorem]], <math>\begin{aligned} 101^4 + 256 &= (100 + 1)^4 + 256 \\ &= (100^4 + 4\cdot 100^3 + 6 \cdot 100^2 + 4 \cdot 100 + 1) + 256 \\  &= 104060401 + 256 = 104060657, \end{aligned}</math> and so the sum of the digits is <math>1+4+6+6+5+7 = \boxed{29}.</math>
  
 
== See also ==
 
== See also ==
{{Mock AIME box|year=Pre 2005|n=1|num-b=8|num-a=10|source=14769}}
+
{{Mock AIME box|year=Pre 2005|n=5|num-b=11|num-a=13|source=28368}}
  
 
[[Category:Introductory Algebra Problems]]
 
[[Category:Introductory Algebra Problems]]

Latest revision as of 19:01, 23 March 2017

Problem

Let $m = 101^4 + 256$. Find the sum of the digits of $m$.

Solution

By the binomial theorem, $\begin{aligned} 101^4 + 256 &= (100 + 1)^4 + 256 \\ &= (100^4 + 4\cdot 100^3 + 6 \cdot 100^2 + 4 \cdot 100 + 1) + 256 \\  &= 104060401 + 256 = 104060657, \end{aligned}$ and so the sum of the digits is $1+4+6+6+5+7 = \boxed{29}.$

See also

Mock AIME 5 Pre 2005 (Problems, Source)
Preceded by
Problem 11
Followed by
Problem 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15