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# Variable formula

**472**✭✭✭

Hello All. Can't figure out how to make this work: (#array_length-(#squre_sides*#number_instances))/#number_instances-1.

#array_length = dimension assigned to total length of a linear pattern of squares.

#square_sides = length of a side of a square.

#number_instances = number of squares in the pattern

What I'm after in the equation result is the spacing between squares. The formula works in Excel. (Add up all the squares side lengths, subtract that from total distance the squares span, and divide that by the number of spaces between the squares)

Trying:

(#array_length-(#squre_sides*#number_instances))/#number_instances-1 = 'Cannot subtract length and unitless number'

(#array_length-(#squre_sides*#number_instances)**in**)/#number_instances-1 = 'Cannot subtract length and area'

(#array_length-(#squre_sides*#number_instances))**in**/#number_instances-1 = 'Cannot subtract area and unitless number'

Any suggestions appreciated. - Scotty

## Comments

402Order of operations:

`(#array_length-(#squre_sides*#number_instances))/#number_instances-1`

is different from

`(#array_length-(#squre_sides*#number_instances))/(#number_instances-1)`

472✭✭✭Thank You. The formula now works. However, I don't think I'll be able to use the function as I wanted to. What I intended was to create an array, stipulating the length of the array and then be able to tweek the array instances within that length. If I increase the instances they populate outside of that length, not within it. I guess that's just the way it works

Something else I don't understand is why dimensions in the sketch are red. If I delete one of the dimensions that are used in the formula, the sketch goes black as if one of those dimensions is in conflict with another. But the adding those dimensions does add up to the length of the array's dimension. Any ideas?