Number
What are numbers? Numbers are basically a set of standard symbols, numerals, that represent quantities. In addition to their use in counting and measuring, numerals are often used for labels (as with telephone numbers), for ordering (as with serial numbers), and for codes (as with ISBNs).
Digits A digit is any of the ten symbols 0 to 9. Using a combination of these digits will form numbers of any size. The ten digits are
0123456789 In the base 10 numeral system, the system we use today for mathematical operations, the symbols for natural numbers are written using ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. In this base 10 system, the rightmost digit of a natural number has a place value of 1, and every other digit has a place value ten times that of the place value of the digit to its right.
Number – Place Value Our system of writing numbers is called the decimal system, because it is based on ten, the number of fingers and thumbs we have. The decimal system uses the digits 0 1 2 3 4 5 6 7 8 9 The place of the digit in a number tells you the value of that digit.
Place Value The value of a digit depends on its place in the whole number TU e.g. In the number 72 the value of the seven is 7 tens or 7 TU Whereas: In the number 37 the seven has the value of 7 units
Practice – Place Value
Fill in the boxes to show the value of each figure. The first two are done for you.
1)
67
6
tens and
7
units
2)
4
0
tens and
4
units
3)
28
tens and
units
4)
95
tens and
units
5)
6
tens and
units
6)
9
tens and
units
7)
80
tens and
units
8)
34
tens and
units
Place Value To work out the value of large numbers we can put the figures in columns, with the value of each column at the top. • Examples
Thousands (Th)
Hundreds (H)
Tens (T)
Units (U)
6
2
4
5
Six thousand, two hundred and forty five
Place Value Numbers with Zeros The zero in a number plays a very important part in deciding its value
Four hundred is written: HTU 400
We need to put in two zeros to show that it is four hundred and not just four, the zero is known as the place holder and occupies that column
Place Value Numbers with Zeros Six hundred and seven is written: HTU 607 We need the zero to show that there are no tens
Practice - Place Value Fill in the boxes to show the value of each figure . The first two are done for you. 1)
584
5
hundreds
8
tens
4
units
2)
690
6
hundreds
9
tens
0
units
3)
708
hundreds
tens
units
4)
302
hundreds
tens
units
5)
4290
thousands,
hundreds
tens
units
6)
5060
thousands,
hundreds
tens
units
7)
2100
thousands,
hundreds
tens
units
8)
3009
thousands,
hundreds
tens
units
Larger numbers Bil lio ns
Hu nd re d mi lli on
Te n mi lli on
Mi lli on s
Hu nd re d th ou sa nd s
Te n th ou sa nd s
Th ou sa nd s
Hu nd re ds
Te ns
Un its
B
HM
TM
M
H Th
T Th 8
Th 7
H 5
T 2
U 9
The number 87 529 has 8 ten thousands, 7 thousands, 2 tens and 9 units Eighty-seven thousand, five hundred and twenty-nine