Page 77 - Math Smart - 7

Decimals

Ancient civilisations had their own numeral systems. The ancient Egyptians used the
decimal system (base-10), the Babylonians used a base-60 system. Some civilisations used
a base-20 system. We use a base-10 system called the decimal system or the Hindu-Arabic
System. The decimal system uses 10 numerals-0, 1, 2, 3, 4, 5, 6,1, 8 and 9. All numbers in
the decimal system are made using a combination of these 10 numerals. It is thought that
the decimal system may have been based on counting with our 10 fingers.

The ancient Egyptian number system was also a base-10 system. The table below shows
the symbols used in the ancient Egyptian number system and the symbols used in the
decimal system.

I n e. \ %

stroke heelbone coiled rope lotus flower pointed finger tadpole scribe
1 10 100 1000 10 000 100 000 1 000 000

You will learn about:
In this
Understanding decimals
unit
Ordering decimals
Rounding decimals

Adding and subtracting decimals
Multiplying and dividing decimals
by 10,100 and 1000
Multiplying decimals

Dividing decimals

Estimating and approximating

Try and Apply!

I Use the ancient Egyptian
-j
; number system symbols to
;^| represent the number 123.