COMBINA in Collabora Office: Count Unordered Selections with Repetition

• Introduced: original Collabora release and launch date are not established by the sources reviewed.
• Availability: documented in Collabora Office 26.04 help, scoped to the desktop-help release.
• Platform scope: support in every online or mobile deployment is not inferred from desktop documentation.
• Checked: October 14, 2026. Function-specific documentation and independently derived controls; no native Collabora test was performed.

=COMBINA(count1;count2)

count1 is the number of available item types; count2 is the number selected. Order does not matter and repetition is allowed. In the positive-type, nonnegative-integer controls here, the mathematical count is:

(count1+count2-1)! / (count2!*(count1-1)!)

The official Collabora page gives this relationship. It describes combinations of a multiset, not permutations or a selection from limited physical stock. The examples use English function names and semicolon separators.

Suppose the available types are A, B and C, and two items are selected. The six possibilities are AA, AB, AC, BB, BC and CC. AB and BA are the same unordered selection, while AA is allowed.

=COMBINA(3;2)

Expected result: 6. This direct enumeration checks both parts of the definition. Counting ordered pairs would instead give nine possibilities, a different problem.

Keep four available types and enter selection sizes 0, 1, 2, 3, 4 in A2:A6. In B2 enter and fill down:

=COMBINA(4;A2)

Expected counts are 1, 4, 10, 20, 35. The zero-size mathematical control counts the one empty selection. It does not mean an actual order was placed.

Choosing more items than there are types is meaningful because types may repeat. For example, =COMBINA(2;4) has expected count 5, corresponding to AAAA, AAAB, AABB, ABBB and BBBB.

A fictional sampler contains three scoops chosen from four flavours and two toppings chosen from three types. Repeated flavours and toppings are allowed; order within each group is irrelevant. Use:

=COMBINA(4;3)*COMBINA(3;2)

Expected result: 120, from 20 flavour selections multiplied by 6 topping selections. This multiplication assumes the two choices are independent. A rule prohibiting a certain topping with a flavour would invalidate that simple product and require explicit constraint handling.

Record the model assumptions beside the result. COMBINA cannot inspect stock limits, eligibility rules or whether two named categories actually represent different types.

For four types and three choices:

=COMBINA(4;3)
=COMBIN(4;3)

Expected counts are 20 and 4. COMBIN counts the no-repetition selection. Neither expression counts the order in which the items are selected.

A separate ordered-with-repetition model would have 4^3, or 64, possibilities. Keeping all three results together helps expose a mistaken counting model before it is copied into a larger calculation.

For the same four-type, three-choice case:

=FACT(4+3-1)/(FACT(3)*FACT(4-1))

Expected result: 20. FACT supplies the factorials. Use this only as a small transparent control; separately forming factorials can create unnecessarily large intermediate values for bigger inputs.

This guide deliberately uses whole-number counts with at least one available type. The direct source does not establish a complete fractional-input, negative-count, zero-type or overflow error matrix. Do not assume truncation or a specific error label from another spreadsheet product.

Before accepting a count, ask whether order matters, whether repetition is allowed and whether any finite stock limit applies. A mathematically valid count for the wrong model is still an incorrect answer to the real question.

• Collabora Office 26.04: COMBINA.
• Editorial testing standards.

The direct product reference establishes the function definition and syntax. Worked examples were independently calculated; no native Collabora execution or broader client certification is claimed.