Replace space with comma: =SUM(A1:A10 B1:B10) → =SUM(A1:A10, B1:B10) The comma is the union operator — sums both ranges.

Why does #NULL! keep appearing?

Typed a space where a comma should separate arguments: =SUM(A1:A10 B1:B10). Typed a space where a colon should make a range: =SUM(A1 A10). Intended intersection that does not actually overlap.

How to prevent #NULL! in the future?

Use function autocomplete — Excel inserts correct separators. Avoid manually typing ranges with spaces.

Spreadsheet error

How to fix the #NULL! error

TL;DR

#NULL! means the formula used the intersection operator (a space) between two ranges that do not actually intersect. Usually a typo — you meant a comma.

What it means

In Excel, a space between two ranges is the intersection operator. =SUM(A1:A10 B1:B10) means "sum the cells that are in both ranges" — which is none of them. This returns #NULL!.

Common causes

•Typed a space where a comma should separate arguments: =SUM(A1:A10 B1:B10).
•Typed a space where a colon should make a range: =SUM(A1 A10).
•Intended intersection that does not actually overlap.

How to fix it

1.Replace space with comma

=SUM(A1:A10 B1:B10) → =SUM(A1:A10, B1:B10)
The comma is the union operator — sums both ranges.

2.Replace space with colon for a range

=SUM(A1 A10) → =SUM(A1:A10)
The colon makes it a range from A1 through A10.

Example

Broken=SUM(A1:A10 B1:B10)Fixed=SUM(A1:A10, B1:B10)

The space operator asks Excel to sum only cells in both ranges (intersection). Since they do not overlap, the result is #NULL!. Replace the space with a comma to sum both ranges.

Prevention

Use function autocomplete — Excel inserts correct separators.
Avoid manually typing ranges with spaces.

Related errors

#REF!#NAME?#VALUE!

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