Subtraction in base 8 - Math Central

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Question from Adi, a student:

Hi!
Can you help me with a nagging problem, I searched a lot over the web and couldn't find it.
I saw this site I gave it a try and I found it to my liking.

I am confused how to subtract bases from other bases:
567 (in base 8)
- 456 (in base 8)
______________
?????????
How do you do this? I do know how to carry and subtract with different bases. Can
you please help me?

Thanks,
Adi

Hi Adi,

You don't need to carry or borrow to do this subtraction. 7-6=1, 6-5=1 and 5-4=1 and hence

567₈ - 456₈ = 111₈.

You can verify by converting to base ten.

\[567_8 = 5\times 8^2 + 6\times 8 + 7 = 375.\]

Convert 456₈ and 111₈ to base ten and check that the difference is correct.

Write back if you need more assistance,
Penny

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