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## AP®︎/College Computer Science Principles

### Course: AP®︎/College Computer Science Principles>Unit 1

Lesson 2: Binary numbers

# Decimal system refresher

AP.CSP:
DAT‑1 (EU)
,
DAT‑1.C (LO)
,
DAT‑1.C.1 (EK)
,
DAT‑1.C.3 (EK)
Review how the decimal number system works before diving into the binary number system. The decimal number system and binary number system work the same way; the only difference is what each digit represents (0-9 versus 0/1). Created by Pamela Fox.

## Want to join the conversation?

• The decimal system works well for rational numbers, but what about irrational numbers like Pi? Is there a way to show these numbers in the decimal system? Or, is the decimal system inherently limited to representing certain kinds of numbers (e.g., rational numbers)?
• The decimal system cannot fully express irrational numbers as all irrational numbers will require an infinite number of digits to be completely written out. The decimal system can only write out rational approximations for irrational numbers by rounding after a certain number of decimal places.
• what about irrational numbers like Pi?
(1 vote)
• This is an excellent point. Irrational numbers have infinite representations, so they can only be approximated by finite representations in computers.

so Pi would be truncated to something like 3.1415 instead of 3.14159265...

Hope this helps
• What's the difference? You don't know how much of it would happen? I am not sure if I am not sure what you're going for? If you're going into this game then you can get a lot better we have is the best thing that can get
(1 vote)