Add number count to following row?

Question

I have a formula for

$D2 = $A1+$B2*($C1+$D1) 

and

$D3 = $A2+$B2*($C2+$D2). 

How do I make

$D4 = $A3+$B2*($C3+$D3) 

and so on?

Answer 1

In D2 Make it

 =$A1+$B$2*($C1+$D1)

and then drag it down. The $ in front of the 2 in $B$2 tells excel to never change that reference from B2

This is called Absolute referenceing you can learn more From This Answer