Difference between revisions of "1976 AHSME Problems/Problem 5"
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How many integers greater than <math>10</math> and less than <math>100</math>, written in base-<math>10</math> notation, are increased by <math>9</math> when their digits are reversed? | How many integers greater than <math>10</math> and less than <math>100</math>, written in base-<math>10</math> notation, are increased by <math>9</math> when their digits are reversed? | ||
Revision as of 19:06, 12 July 2020
Problem 5
How many integers greater than 
and less than 
, written in base- notation, are increased by 
when their digits are reversed?
Solution
Let our two digit number be 
, where 
is the tens digit, and 
is the ones digit. So, 
. When we reverse our digits, it becomes 
. So, 
. So, our numbers are 
.
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