The SUMSQ function syntax has the following arguments: Number1, number2, ... Number1 is required, subsequent numbers are optional. 1 to 255 arguments for which you want the sum of the squares. You can also use a single array or a reference to an array instead of arguments separated by commas.
THEY/THEIR (SINGULAR). Using the plural pronoun to refer to a single person of unspecified gender is an old and honorable pattern in English, not a newfangled bit of degeneracy or a politically correct plot to avoid sexism (though it often serves the latter purpose).
When a subject is made up of two elements joined by or or nor, the verb is singular if both elements are singular. If one of the elements is plural, the verb becomes plural. For example: 1  Shortbread or cake is on offer.  Chocolates or cake are on offer.