Caretec DoubleCheck, User Manual

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Every value, every result is announced by the speechoutput. To repeat the result of 
the last calculation, press the Equals-key once again. If you accidentally type in a 
wrong digit, just press ON-key long (3 x 3 group, row 1, right key) to delete the last 
value.  
 

5.2:  Advanced Arithmetic Functions 

DoubleCheck XL also offers the possibility to calculate percentages, extract square 
roots or square a given number. 
 

5.2.1:  Percentages 

When calculating percentages the following approaches are most common: 
 

Calculation Example 

Input 

Percent 

How much is 5% of 250? 

250 x 5% 

Percentage 

250 is 5% of how much? 

250 / 5% 

Surcharges 

How much is 250 plus a surcharge of 5%? 

250 + 5% 

Rebate 

How much is 250 minus a rebate of 5 %? 

250 – 5% 

   
To calculate for example, how much are 5% of 250, type 250, shortly press the 
multiplication key (4 x 4 group, row 2, right key) followed by the digit 5. Finish the 
process by shortly pressing the percent-key (3 x 3 group, row 3, right key). 
DoubleCheck XL will then announce the result. 
 

5.2.2:  Square a Given Number 

To square a given number, type in the value and shortly press the squared-key (3 x 
3 group, row 3, middle key) followed by the equals key. 
 

5.2.3:  Extract a Square Root 

To extract a square root, type in the number and shortly press the square root key 
(3 x 3 group, row 3, left key) followed by the equals key. 
 

5.2.4:  Reciprocal Value 

To calculate the reciprocal value, type in a number and press and hold the percent-
key (3 x 3 group, row 3, right key) followed by the equals key. 
 

5.2.5:  To the Power of 

Type in a number, press and hold the square-key (3 x 3 group, row 3, middle key) 
until you hear „to the power of“. Now type in the number needed and finish the 
calculation by shortly pressing the equals key (4 x 4 group, row 4, column 3).  
 

5.2.6:  

Π

 (Pi) 

To calculate with the number Pi, press and hold the square root key (3 x 3 group, 
row 3, left key).