You are correct. 2718 + 1178 = 4108, as shown below.
1
1
← carry
2
7
18
+
1
1
78
=
4108
, not 4008
Now let’s have a look at multiplication in the octal system. Again, as long as the numbers stay below 108 (810, that is), octal and decimal multiplication are identical.
28 × 28 = 48
28 × 38 = 68
But 28 × 48 = 108, etc.
If you want to be really good at multiplication in the octal system, you’ll have to master the octal multiplication table given on p. 469. One number you must learn to multiply with is 128. This is the multiplier you will use in converting octal fractions to decimals.
Using the table below, let’s multiply a number by 128. What is
