Question

The sum of the digits of a three-digit number is 6. The hundreds digit is twice the units digit, and the tens digit equals to the sum of the other two. Find the number.

Answer 1

a+b+c=6, a=2c, b=a+c using a and b in the first equation gives you:

2c+a+c+c=6 now use a=2c again

2c+2c+c+c=6

6c=6

c=1, since a=2c

a=2, since b=a+c

b=3

So the number is 231.