Calculating percentages I have a Casio MJ 100. It seems incapable of accurately calculating percentages. If I type in 100 minus 20% it answers 400! Is it time to throw it away?

It is used for calculating markup. For example, if you have an item at $100 and have a 20% markup, you get $120.


http://support.casio.com/storage/en/manual/pdf/EN/004/MJ-100D_MJ-120D_EN.pdf

best way to calculate percentages quickly is to multiply base number (100) by 1.xx (where xx is the percentage desired - here it would be 10 or just 1)

100*1.1=110

Works on every calculator every time.

On most Casio calculators you must type: '175 x 20 % -' (and '+' is for adding a percentage)

Here is a sample of the percentage calculations that the calculator can perform. You will not see among them the conversion from decimals to percentages.
To convert from decimals to percents move the decimal mark 2 places to the right and append the % sign.
To convert from percents to decimals, move the decimal mark 2 places to the left.

1÷1700 expressed as a decimal is 0.000588235, which is 5.882...×10^-4. [NB not 10^4]

To convert this to a percent, remember that "per cent" means "per 100" which also means "divide by 100". To keep the answer correct, if you are dividing by 100 you must also multiply by 100.

The get the answer in percent, you must therefore multiply the previous answer by 100 to get 0.00588235 percent. (or 5.882...×10^-2 percent).

FINALLY figured out how to change the tax rate! Press AC. Press and hold the Rate Set (%) button UNTIL THE CURRENT TAX RATE IS DISPLAYED. Enter the new rate you want (such as 7.5). Press the Rate Set (%) button again.

Big calculators work a little different than handheld calculators. Like the above commentor explained, if you have a basic "whats 100 minus 20?" You have to entered as 100 + 20 -- And when you hit the minus button at the end, it will give you the total. 100 is the positive number, and the 20 is the negative number that your subtracting. Also you can hit 20 -- 100 + and get the same total because you entering 20 as the negative and 100 as the positive, just in reverse.

I have a Casino MS-80S and yea, the percentage works different. As example to take 100 and subtract 10%, this is what I do: 100 X 10% - and then I get the answer 90 after I press the minus key. To add the percentage instead, 100 X 10% + will give me an answer of 110, after I press the plus key.

I found it by myself, I can help you.
1. Press (AC)
2. Hold (Rate) for about 2-3 second
3. Press (Set / TAX+)
4. Input the tax rate
5. Press (Set / TAX+)
6. Hold (Rate) for about 2-3 second again
7. Press (Set / TAX+) again
And Then you can test the rate .

From Thailand

From the manual:

Function: Keys
Answer
Percentage: 100 x 5% 100 x 5 % 5

Add On: 100 + (100 x 5%) 100 x 5 % + 105

Discount:10 - (10 x 20%) 10 x 20 % - 8

Ratio: 30 = 60 x ?% 30 (division key) 60 % 50

% change: 12 = 10 + (10 x ?%) 12 - 10 % 20

Mark-up: 25% mark-up of 120 120 = 25% 160
- 40 (profit)