Difference between revisions of "2023 AMC 10A Problems/Problem 12"
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| − | Multiples of 5 always end in 0 or 5 and since it is a three digit number, it cannot start with 0. All possibilities have to be in the range from 7 x 72 to 7 x 85 inclusive. 85 - 72 + 1 = 14. | + | Multiples of 5 always end in 0 or 5 and since it is a three digit number, it cannot start with 0. All possibilities have to be in the range from 7 x 72 to 7 x 85 inclusive. 85 - 72 + 1 = 14 (B). |
~walmartbrian ~Shontai | ~walmartbrian ~Shontai | ||
Revision as of 16:45, 9 November 2023
How many three-digit positive integers 
satisfy the following properties?
- The number
is divisible by 
.
.- The number formed by reversing the digits of is divisble by
.
.
Solution 1
Multiples of 5 always end in 0 or 5 and since it is a three digit number, it cannot start with 0. All possibilities have to be in the range from 7 x 72 to 7 x 85 inclusive. 85 - 72 + 1 = 14 (B).
~walmartbrian ~Shontai
