Place Value
Numbers are made up of digits. Where a digit is placed in a number is known as it's place value.
Th. H. T. U.
2 3 8 7
In the number 2387
• the value of 2 is 2000
• the value of 3 is 300
• the value of 8 is 80
• the value of 7 is 7
Two thousand, three hundred and eighty-seven.
Adding and subtracting whole numbers.
Addition example:
188+77= 265
188
+ 77
---------
265
---------
1 1 1
Subtraction example:
175-81=94
01
175
- 81
--------
94
--------
I couldn't do 7-8 so I took 1 away from the number next to it (which in this case was 1, now changing the 1 to a 0) and put 1 next to 7 to make it 17. Then I did 17-8=9.
Multiplying and dividing with powers.
• the powers you need to know are 10,100,1000.
Multiplying
To multiply by a power you move the number 1,2 or 3 places to the left.
Example:
13x100=1300
Th. H. T. U.
1 3
1 3 0 0
x10= move 1 place to the left
x100= move 2 places to the left
x1000= move 3 places to the left
Divide
To divide by a power you move 1,2 or 3 places to the right.
Example:
17 / 10= 1.7
Th H T U • th h t u
1 7
1 • 7
Long multiplication
136x72= 2792
X 100 30 6
70 7000 2100 420
2 200 60 12
7000
+2100
420
200
60
12
-------------
2792
-------------
Long division
312/12= 26
26
____
12| 312
24
_____
72
72
____
0
• 12 couldn't divide into 3 so you move on to the next number.
• 31/12 goes 2 times.
12x2=24. Then write 24 below 31 then subtract to get 7.
• bring down the 2 to make the number 72. 12 goes into 72 six times. 12x6=72
312/12= 26
Example 2
630/18=35
35
____
18 | 630
54
_____
90
• divide 63 by 18
• 3x18=54
• 63-54=9. Bring down the 0 then divide 90 by 8 [=5]
