2007 AMC 8 Problems/Problem 18: Difference between revisions

Revision as of 19:20, 7 June 2011

$303\times505=153015$

The ones digit plus thousands digit is $5+3=8$ .

$30303\times50505=1530453015$

Note that the ones and thousands digits are, added together, $8$ . (and so on...) So the answer is $\boxed{D}$ $(8)$ .

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-When you multiply <math> 303 </math> by <math> 505 </math>, it's <math> 153015 </math>. The ones digit plus thousands digit is <math> 5 </math> <math> + </math> <math> 3 </math> <math> = </math> <math> 8 </math>. <math> 30303 </math> <math> \times </math> <math> 50505 </math> <math> = </math> <math> 1530453015 </math>. Note that the ones and thousands digits are, added together, <math> 8 </math>. (and so on...) So the answer is <math> \boxed{D} </math> <math> (8) </math>.
+<math>303\times505=153015 </math>
+The ones digit plus thousands digit is <math>5+3=8</math>.
+<math> 30303\times50505=1530453015</math>
+Note that the ones and thousands digits are, added together, <math>8</math>. (and so on...) So the answer is <math> \boxed{D} </math> <math> (8) </math>.