COMBINA Function
Calculate the number of combinations along with repetitions for a given number of items
Calculate the number of combinations along with repetitions for a given number of items
The COMBINA function is a Math and Trigonometry function. It will calculate for a given number of items the number of combinations along with repetitions. The function was introduced in MS Excel in 2013 and hence not available in earlier versions.
=COMBINA(number, number_chosen)
The COMBINA function uses the following arguments:
To understand the uses of the COMBINA function, let’s consider a few examples:
Suppose we are given six numbers: 1, 2, 3, 4, 5, 6. Now let’s see how the COMBINA function calculates the number of combinations (with repetitions) for other numbers of objects taken from a set of 4.
For any six objects – a, b, c, d, e, f – there are 21 different combinations (with repetitions) of 2 objects. These are:
aa, ab, ac, ad, ae, af, bb, bc, bd, be, bf, cc, cd, ce, cf, dd, de, df, ee, ef, ff
The COMBINA function helps derive such combinations. It uses the formula (n+m-1) ÷ (n-1) where n is the number and m is the number_chosen. Remember the results of COMBINA above include repetitions.
Let’s see some interesting things about COMBINA. If you enter following arguments in a COMBINA function, the results will be:
COMBINA(0,0) is the only non-error output when n=0 yet this should be equal to COMBIN(-1,-1), which returns an error. It implies that the function includes an exception of n-m=0.
The COMBIN and COMBINA functions differ in the following ways:
Click here to download the sample Excel file
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