How to Fix “Missing Number, Treated as Zero” with \multirow

The message “Missing number, treated as zero” often appears in a table when \multirow receives its arguments in the wrong order. In particular, LaTeX expects a number of rows as the first argument; an asterisk in that position triggers the error.

For an automatically sized cell spanning two rows, write \multirow{2}{*}{Text}. The * belongs in the width argument, not the row-count argument.

Use the correct argument order

The basic command is:

\multirow{number of rows}{width}{text}

For example, \multirow{2}{*}{Group A} spans two rows. The first argument, 2, says how many rows the cell covers. The second argument, *, tells the package to use the natural width of the text.

This is the incorrect order:

\multirow{*}{2}{Group A}

Here the first argument is *, but LaTeX needs a row count there. It tries to read a number, encounters the asterisk, and reports the missing-number error. Swap the arguments:

\multirow{2}{*}{Group A}

Minimal working example

The multirow package provides \multirow. This complete example creates a cell that spans two rows:

\documentclass{article}
\usepackage{multirow}

\begin{document}

\begin{tabular}{|c|c|}
\hline
\multirow{2}{*}{Group A} & First row \\
\cline{2-2}
                          & Second row \\
\hline
\end{tabular}

\end{document}

In the second row, the first-column entry is left blank because the Group A cell already occupies that position across both rows. \cline{2-2} draws a horizontal rule only below the second column; a full-width \hline there would run through the multirow cell.

If the error remains

Check the command and nearby table syntax in this order:

1. Inspect the first argument. It should be a row count, such as 2, not * or text.
2. Check the braces. A missing or misplaced brace can shift the arguments, making LaTeX read the wrong material as the row count.
3. Confirm the package is loaded. Put \usepackage{multirow} in the preamble. If the command were simply undefined, LaTeX would generally report an undefined-control-sequence error instead, but loading the package is still required.
4. Check the table row endings. Separate rows with \\, and use & to separate columns. An extra & or a missing \\ can cause a different alignment error nearby.

Common mistakes

• Putting the width star first: \multirow{*}{2}{Text} is wrong; use \multirow{2}{*}{Text}.
• Confusing row count and width: the first argument controls how many rows the cell spans; the second controls its width. A width can be * or a dimension such as 2cm.
• Filling the covered cells again: for a two-row span, leave the corresponding cell blank in the next row rather than entering another value in that same column.

If you intentionally need a fixed-width cell, keep the same argument order and specify a dimension, for example \multirow{2}{2cm}{Group A}.