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 20:06, 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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