Divisibility again

Number Theory Level 2

If a 679 b a679b is divisible by 72,where a and b are unequal digits,then a + b = ?

8 14 6 5

Sakanksha Deo by Sakanksha Deo , 23, India

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2 solutions

Ankita Chaturvedi
Mar 14, 2015

Use divisibility conditions for 8 and 9 and then proceed

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Ravi Dwivedi
Jul 6, 2015

8|79b So b=2

9|a+6+7+9+b
So9|a+24
a=3

a+b=5

0 Helpful 0 Interesting 0 Brilliant 0 Confused

Moderator note:

Simple standard approach.

FYI To start a new line, use the markdown syntax of leaving 3 empty spaces at the end of the line. This makes it easier to read what you wrote. I've edited your solution for your reference.

Calvin Lin Staff - 5 years, 11 months ago

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Thanks for editing

Ravi Dwivedi - 5 years, 11 months ago

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