The IF function is very versatile and can be nested within other functions like SUM or VLOOKUP to create more complex conditional calculations in Excel. Here are two common ways to combine them:

1. IF function within SUM:

This is useful when you want to sum values based on a specific condition.

Example: You have a sales data table with a "Sale Amount" column and a "Region" column. You want to calculate the total sales for the "North" region.

Formula:

```excel
=SUM(IF($B$2:$B$10="North",$A$2:$A$10,0))
```

Explanation:

- `SUM`: This function adds up the values in a range.
- `IF`: This function checks a condition.
- `$B$2:$B$10`: This is the range of cells in the "Region" column to check.
- `"North"`: This is the condition we're checking for (region equals "North").
- `$A$2:$A$10`: If the condition is true (region equals "North"), this range (containing sales amounts) is included in the sum.
- `0`: If the condition is false, this value (0) is included in the sum (effectively excluding that row from the total).

2. VLOOKUP within IF:

This is useful when you need to look up a value based on a condition and then use that value in a calculation.

Example: You have an employee data table with an "Employee ID" column and a "Salary" column. You have a separate table with "Department" names and corresponding "Bonus" percentages. You want to calculate the total salary plus bonus for each employee, but the bonus percentage depends on the department.

Formula:

```excel
=C2+IF(VLOOKUP($B2,Dept_Table!$A:$B,2,FALSE)*C2>50,50,VLOOKUP($B2,Dept_Table!$A:$B,2,FALSE)*C2)
```

Explanation:

- `C2`: This is the cell containing the employee's base salary.
- `IF`: This function checks a condition based on the result of VLOOKUP.
- `VLOOKUP`: This function looks up the employee's department ID (in cell `B2`) in the "Dept_Table" (range `$A:$B`). The `2` indicates returning the value from the second column (bonus percentage).
- `$B2`: Employee ID to lookup.
- `Dept_Table!$A:$B`: Range containing department IDs and bonus percentages in the separate table.
- `FALSE`: This ensures an exact match for the lookup.
- `*C2`: This multiplies the bonus percentage (returned by VLOOKUP) by the employee's salary.
- `>50`: This checks if the calculated bonus amount is greater than 50.
- `50`: If the bonus is greater than 50, a maximum bonus of 50 is used (you can adjust this value).
- `VLOOKUP...*C2`: If the bonus is less than or equal to 50, the calculated bonus amount is used.

These are just a couple of examples. You can nest the IF function within other functions like SUMIFS, AVERAGEIFS, COUNTIFS, etc., depending on your specific needs to create powerful conditional calculations in Excel. Remember to adjust the cell ranges, criteria, and calculations within the formulas to match your specific data and requirements.