Two Parallel Resistors
R_{1} =  R_{T}R_{2} 
R_{2}  R_{T} 
R_{2} =  R_{T}R_{1} 
R_{1}  R_{T} 
R_{T} =  R_{1}R_{2} 
R_{1} + R_{2} 
R_{1}:  
R_{2}:  
R_{T}:  
How To Use:
 Fill in all but one box, hit the Solve button and the unfilled box will be computed.
 In resistor boxes, use: 'k''M''G''m'. For instance: "1k" for 1000Ω.
 Use Clear to empty a box and thus clear* the way for Solve to compute a new value.
Voltage Divider
V_{top}:  
R_{1}:  
R_{2}:  
V_{OUT}: 


I_{div}:  
How To Use:
 Fill in all but one box (or in some cases two boxes can be empty — both R1 & R2, for instance), hit the Solve button and the unfilled box(es) will be computed.
 In resistor boxes, use: 'k''M''G''m'. For instance: "1k" for 1000Ω.
 In current boxes, use: 'A''mA''uA''nA'. For instance: 12mA for .012 amps
 Use Clear to empty a box and thus clear* the way for Solve to compute a new value.
LM317
I_{Adj} 

R_{1}:  
R_{2}:  
V_{out}:@ V_{Ref} 1.20V: 
I_{R1}: 

V_{out}:@ V_{Ref} 1.25V: 
I_{R1}: 

V_{out}:@ V_{Ref} 1.30V: 
I_{R1}: 

How To Use:
 Fill in all but one box, hit the Solve button and the previously unfilled box will be populated with a computed result.
 In resistor boxes, use 'k''M''G''m'. For instance: 1k for 1000Ω.
 Use Clear to empty a box and thus clear* the way for Solve to compute a new value.
 Clicking on the I_{Adj} radio buttons, will automatically solve if at least two values are present.
 There are three Vout results merely because 1.25V is the nominal value [i.e. the voltage we all hope it is]. The manufacturer's guarantee is a voltage between 1.20 and 1.30, thus the two extra cases [BTW: only the center value is editable  the other two will update as needed].

The I_{R1} values go
Red when below recommended load current [5ma].
TLC5916
R_{1}[Ω]: 

I_{LED}[ma]: 
below recommended 3ma. 

How To Use:
 Fill in all but one box, hit the Solve button and the unfilled box will be computed.
 In resistor boxes, use: 'k''M''G''m'. For instance: "1k" for 1000Ω.
 In current boxes, use: 'A''mA''uA''nA'. For instance: 12mA for .012 amps
 Use Clear to empty a box and thus clear* the way for Solve to compute a new value.
*Pun intended!