 # Subtraction question

Hello all, I’m quite new to this forum,
so forgive me if I break a few rules unknowingly

anyways, I have a question : how would one subtract a list of numbers in
a row?

for example,

a = 1
b = 7
c = 3
d = 5
e = 9

I want to subtract all the numbers in this format :

a - b - c - d - e = ?

(keep in mind that there won’t always be 5 numbers, and the numbers
won’t always be constant)

–swaraj

swaraj dhumne wrote in post #1048821:

anyways, I have a question : how would one subtract a list of numbers in
a row?

What have you tried so far? Is this a homework question?

a = [1, 7, 3, 5, 9]

Then take the first element as the initial sum, and make a loop which
iterates over the remaining elements, subtracting them from the sum.

To get all elements apart from the first, use a[1…-1]

There are much more concise ways of doing this in Ruby, but you should
know. Then you can come back and ask if there is a neater way.

hello

2 + 3 + 7 = (2 + 3) + 7 = 2 + (3 + 7) = 12

on the contrary, subtraction is non-associative;
so (5 - 3) - 2 (=0) is not equal 5 - (3 - 2) (=4)

in other word the result depends on parenthesis;

no parenthesis means evaluating from left to right;
so…
a - b - c - d - e = ((((a - b) - c) - d) - e)