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Monday, May 4, 2020

maths

Converting between decimals and percentages is easy when you know what to look for. 
Remember that 1.00 = 1 whole = 100% - these things are all the same. 
So 0.50 will be 50%, 0.30 = 30%, 0.10 is 10%. 


E.g. using different place value positions
12.87 = 1,287%
4.56 = 456% 
1.42 = 142%
0.56 = 56%
0.09 = 9%
0.005 = 0.5%


*Remember to check your place value*


Change these decimals into percentages (put it next to the decimal).
Decimal
Percentage
Decimal
Percentage
0.12
12%
0.99
99%
0.76
76%
0.76
76%
0.80
80%
0.34
34%
1.00
100%
0.45
45%
2.00
200%
1.23
123%
5.6
560%
0.99
99%
0.44
44%
1.45
145%
0.32
32%
8.65
865%
0.56
56%
1.45
145%
0.09
0.09%
3.65
365%
0.07
0.7%
1.22
122%
1.34
134%
12.09
120.9%
0.23
23%
0.06
6%
0.776
77.6%
0.045
0.45%
0.087
0.87%
0.32
32%
0.124
12.4%
0.08
8%
1.579
157.9%
0.3
3%
2.40
240%
0.04
4%
2.04
204%
0.001
0.1%
0.01
1%
0.012
12%

To change from percentages to decimals, do the opposite.
Percentage
Decimal
Percentage
Decimal
10%
0.10
66%
0.66
20% 
0.20
40%
0.40
15%
0.15
30%
0.30
100%
1.00
0%
0.00
150%
1.50
87%
0.87
200%
2.00
12%
0.12
165%
1.65
1%
0.01
45%
0.45
90%
0.90
90%
0.90
70%
0.70
80%
0.80
60%
0.60
60%
0.60
54%
0.54
65%
0.65
45%
0.45
55%
0.55
87%
0.87
34%
0.34
23%
0.23
12%
0.12
54%
0.54
5%
0.05
29%
0.29
1%
0.01
12%
0.12
4%
0.04
56%
0.56
2%
0.02
23%
0.23
0.5%
0.005
78%
0.78
98%
0.98
56%
0.56
99.5%
9.95
123%
1.23
120%
1.20
134%
1.34
150%
1.50
165%
1.65

Everyone should be able to find 10% of an amount easily, because there is a place value trick to it.
If you are finding harder percentages, there is a formula to use (calculator allowed!)

Finding 10% in your head. Pick up the decimal place and move it one spot to the left -
E.g. $45.00 - move the decimal - $4.50 -- so 10% of $45 is $4.50


Finding 10% in your head

10% of that number
$150.00
$15.00
$65.00
$6.50
$75.00
$7.50
$90.00
9.00
$140
14.00
$120
12.00
$125
12.50
$199.99
19.99
$250
25.00
$49.99
4.99
$1,500
150.00
$4,950
495.95

Finding percentages. 

Amount / total x 100 = 
E.g. 20/35 x 100 = 57%


= Percentage 
14/20
70%
3/15
20%
60/80
75%
45/50
90%
87/90
96.67%
14/30
46.66%
65/80
18.25
17/35
48.57
19/25
76.00
17/20
85.00
16/27
59.25
26/29
89.65
15/28
53.57
13/29
44.82
19/32
59.37
27/46
58.69
19/70
27.14
3/45
6.66
18/95
18.94
14/65
21.53

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