Math CentralQuandaries & Queries


Question from Adi, a student:

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?


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,

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