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1) When a positive integer is expressed in base 7, it is AB base 7 , and when it is expressed in base 5, it is  BA base 5. What is the positive integer in decimal?

 May 26, 2019
 #1
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I went 7A + B = 5B + A

thus    6A = 4B

From this I concluded that A and B are 4 and 6. 

 

(base 7) 46  =  (base 10) 28 + 6 = 34

(base 5) 64  =  (base 10) 30 + 4 = 34

 

The question is what is the integer in decimal.  It's 34

 

.

 May 27, 2019
edited by Guest  May 27, 2019
 #2
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(Guest:   Note....you cannot have a   645     .....  there is no '6'   in base 5 )

 

See other answers here:

https://web2.0calc.com/questions/help-please_24894

 May 27, 2019
edited by Guest  May 27, 2019

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