Re: adding octal
Let's think about it a little.
Base 8 allows the digits 0, 1, 2, 3, 4, 5, 6, 7. What does that say for a problem including the expression 19?
Something fishy going on, there.
Generally, just add them.
In Base 8
16 + 24 =
6+4 = 2 and carry the 1
1+1+2 = 4
Thus 42
Checking in Decimal
16 octal = 8 + 6 decimal = 14 decimal
24 octal = 16 + 4 decimal = 20 decimal
14 + 20 decimal = 34 decimal
42 octal = 32 + 2 decimal = 34 decimal
There it is.