Question

What is the octal number 1548 in base 10?

Answer 1

The octal system uses powers of 8 instead of powers of 10 - so there's a 1 in the 512's place, a 5 in the 64's place, a 4 in the 8's place, and a 8 in the 1's place. Technically, you can't have a digit 8 in base 8 just like you can't have a digit 10 in base 10, but I'll ignore that. So you add up 1*512+5*64+4*32+8*1 = 872.