ADDNUMBERS

ADDNUMBERS(number1 [,number2] [..])
Returns the sum of a group of numbers.

REMARKS
* This function excludes hidden rows.
* Arguments that are logical values are excluded.
* Arguments that are text are excluded.

1 - What is the sum of the numbers 10 and 20.
2 - What is the sum of the numbers 10 and -20.
3 - What is the sum of the numbers 10, 20, 30 and 40.
4 - What is the sum of the numbers 10, 20, 30 and 40 ignoring any logical value arguments.
5 - What is the sum of the numbers 10, 20, 30 and 40 ignoring any text arguments.