A two digit number - Math Central

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Question from JEFFERSON, a student:

The sum of the digits is 6. When the digits are interchanged, the new number represented is 3 time the 10 digit of the original number. Find the original number?

Hi Jefferson,

I can help get you started.

You are looking for a two digit number. Suppose the tens digit is $a$ and the units digit is $b$ then the number is $10 a + b.$ The sum of the digits is 6 so $a + b = 6.$ What number do you get if you reverse the digits? This is 3 times $a$ which gives you a second equation for $a$ and $b.$ solve for $a$ and $b.$

Penny

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