Add all checked items in a column and then convert to number

="Total: " + COUNTIF([Totals Check]:[Totals Check], 1)

=VALUE(RIGHT([All Totals]1, 3))


 Add all checked items in a column (need to use father/child row setup) 

="Total: " + COUNTIF(CHILDREN(), 1)
=COUNTIF(CHILDREN(), 1)

Add all checked items in a column and sum of all integers in another
="Total: " + SUM(COUNTIF(CHILDREN(), 1) + SUM([Extra Qty]:[Extra Qty]))

Add all same items in a column. Example-- Add all cells with the value Kindergarten.
=COUNTIF([Column Name]:[Column Name], "Kindergarten")

Adds integers in a column if criteria from another column is true. Example-- Add up the values for Cost column when Type column value is 'Admissions'.
=SUMIF([Type]:[Type], "Admission", [Cost]:[Cost])

Nested SUMIF formula. Example-- If the values from Type are equal to 'Sponsorship', add values from both 'Fees' and 'Processing' then subtract from 'Total Paid'.
=SUM(SUMIF([Type]:[Type], "Sponsorship", [Total Paid]:[Total Paid]))
	-
		(
			(SUMIF([Type]:[Type], "Sponsorship", [Fees]:[Fees]))
			+ 
			(SUMIF([Type]:[Type], "Sponsorship", [Processing]:[Processing]))
		)