Download Fractions

The Casio FX 115ES Calculator and Fractions, Mixed Numbers and Decimals
These are the buttons we will be using to calculate fractions.
SHIFT
ARROW KEYS
FRACTION
∎
ON
⬚
OFF
Let’s start with the basic arithmetic operations:
3
 ADDITION:
4
1
+5
Start with 3
∎
4 right arrow
𝟑
Your screen should look like: 𝟒 |
Continue with + 1
∎
5 right arrow =
𝟑
+
𝟒
Your screen should look like:
𝟏
𝟏𝟗
𝟓
𝟐𝟎

 SUBTRACTION:
1
3
2
−5
1
∎
3 right arrow - 2
Your screen should look like:
 MULTIPLICATION:
5
2
×3
4
5
∎
𝟏
−
𝟑
4
7
6
÷ 13
4
∎
5 right arrow =
𝟐
𝟏
− 𝟏𝟓
𝟓
4 right arrow X 2
Your screen should look like:
 DIVISION:
∎
𝟓
𝟒
7 right arrow ÷ 6
Your screen should look like:
𝟒
×
∎
÷
𝟕
∎
3 right arrow =
𝟐
𝟓
𝟑
𝟔
13 right arrow =
𝟔
𝟐𝟔
𝟏𝟑
𝟐𝟏
Mixed numbers
These are the buttons we will be using to calculate mixed numbers and improper factions.
SHIFT
ARROW KEYS
FRACTION
SD to access
𝑎
𝒃
𝒅

𝒄
𝒄
𝟐𝟔
The answer from the division problem above was 𝟐𝟏, which is an improper fraction. To convert from an
𝒃
𝒅
improper fraction to a mixed number use the SHIFT SD button to access the 𝑎 𝒄  𝒄 function.
 Input 26
21 right arrow SHIFT SD
Your screen should look like:
𝟐𝟔
𝟓
𝟏 𝟐𝟏
𝟐𝟏
 To convert back to an improper fraction just press SHIFT SD again.
To input a mixed number, you just need to press SHIFT and the fraction key to access the mixed
number option.
3
 3 4 is input by pressing 3 SHIFT
∎
3 down arrow 4
To work with mixed numbers and proper fractions, you just need to input each using the appropriate
buttons.
1
Let’s work 2 4 ÷
2
5
 Input 2 SHIFT
∎
1 down arrow 4 right arrow ÷ 2
1
Your screen should look like: 2 4 ÷
2
𝟒𝟓
5
𝟖
∎
5 right arrow =
SHIFT SD yields
𝟓
5𝟖
Decimal/Fraction Conversions
These are the buttons we will be using to work with decimal conversions.
SHIFT
ARROW KEYS
FRACTION
SD
There are times the decimal rather than the fractional value is needed. To convert a fraction to a decimal
or back the = button must be pressed before pressing SD
𝟓
 To change 5 𝟖 to a decimal, input the mixed number as above:
5 SHIFT
5 down arrow 8 right arrow and then press = which changes the fraction to
improper form. Now press SD and the answer will change to a decimal.
5
Your screen should look like: 5 8
If you press SD again the answer reverts to the improper fraction
𝟓. 𝟔𝟐𝟓
45
8
.
Suppose the fraction does not represent a terminating decimal?
If the problem is looking for an exact answer, you are better leaving your work in fractional form.
If the problem is asking for an approximate answer,
you may convert to a non-termination decimal as a LAST step.
Fractions which have non-terminating decimal representation are given with the line above the repeating
numbers.
2
5
17
becomes 0. 6̅
becomes 0. ̅̅̅̅̅̅̅̅̅̅
714285
becomes 1.416̅
3
7
12
 Pressing the SD again changes decimal to one with 10 decimal places rounding the answer in
the last place.
0. 6̅ becomes 0.6666666667
̅̅̅̅̅̅̅̅̅̅ becomes 0.7142857143
0. 714285
1.416̅ becomes 1.416666667
 Pressing the SD again changes decimal back to its fractional form.
These are the buttons we will be using to work percent problems.
SHIFT
FRACTION
ARROW KEYS
( to access %
SD
To work a problem involving percent you will need to access the % function by first using SHIFT and
then ( .
 To take 25% of 468: Press 25 SHIFT ( X 468 =
Your screen should look like: 25% × 468
1
 To take 123 % of 325: Press 12 SHIFT
∎
𝟏𝟏𝟕
1 down arrow 3 right arrow SHIFT ( × 325 =
1
Your screen should look like: 12 3 % × 325
𝟒𝟖𝟏
𝟏𝟐
𝟏
This answer can be changed to the mix number 𝟒𝟎 𝟏𝟐 by using SHIFT SD or the decimal equivalent
̅ by using just SD .
𝟒𝟎. 𝟎𝟖𝟑
Changing from percent to fraction or decimal is possible by just inputting the percent and pressing =.
 Find 48% as a fraction and a decimal: 48 SHIFT ( =
Your screen should look like: 48%
𝟏𝟐
1
 Find 533% as a fraction and a decimal: 53 SHIFT
1
Your screen should look like: 533%
Pressing SD gives 0.48
𝟐𝟓
𝟖
𝟏𝟓
∎
1 down arrow 3 right arrow SHIFT ( =
̅
Pressing SD gives 0. 𝟓𝟑