☞ It is a What-If Analysis tool.
☞ It allows you to define output results and then shows what input values are needed to generate that result.
☞ It deals with single input value to reach a specific output.
☞ It is also called Back-solving method.
☞ Lets see an example to understand this.
Step 1 : Tools Menu → Goal Seek option
Step 2 : Goal seek dialog box will be displayed → Fill default settings → OK
Formula cell : Select the formula cell where you have applied SI formula (Here is C10).
Target value : Enter 4000, which is desirable.
Variable cell : Select the cell, whose principal amount to be estimated (Here is C6).
Step 3 : LibreOffice Calc dialog box appears → Yes/No button(to insert result or not)