The Number System
We use the Hindu-Arabic system which uses the following ten digits:
0 1 2 3 4
5 6 7 8 9
If a number is greater than 9, we represent it by using two or more
digits which are placed together horizontally.
Our number system uses a place system. This means that the place
value of a digit in a number depends on the column in which the digit is
placed.
E.g. The number 35 is formed by using the digits 3 and 5
representing 3 tens and 5 units respectively.
The number system we use is a 'base 10' system. Therefore, each
'column' in the place value system is a power of 10 as shown below.
This suggests that 685 can be written as follows: - So, 685 is the number six hundred and eighty-five.
-
- Likewise, 3849 can be represented as follows:
 - So, 3849 is the number three thousand, eight hundred and forty-nine.
Example 1
Write 74 in words.
Solution:
74 is the number seventy-four.
Example 2
Write 3 128 659 in words.
Solution:
3 128 659 is the number three million, one hundred and twenty-eight
thousand, six hundred and fifty-nine.
Example 3
What number does the digit 8 in the following numbers represent?
a. 38
b. 82
c. 384
d. 867
e. 8001
f. 186 345
g. 9 351 278
h. 369 481
i. 45 986
j. 283 000
Solution:
The number represented by the digit 8 is:
a. 8
b. 80
c. 80
d. 800
e. 8000
f. 80 000
g. 8
h. 80
i. 80
j. 80 000
Key Terms
place system, place value, base
10 number system, numbers as words, digits
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