I think I need a bit more information.
(first of all, these are "values", not "variables")
You said that the values are in a "chart".
Do you really mean that they are in a list?
A chart  is an image that shows a graphical representation of values.

It looks like you have a column of numbers  (you gave 44 of them)
and you want to find  the next largest number  from a given number.
You said "the numbers do not have a pattern  or are a whole number"
I guess this means that they are basically a set of numbers, either
whole or decimal, not text...

OK...
Let's say, the number you supply is "55".
Vlookup returns 52.26 instead of 58.


Are you set on using excel  functions, not VBA?
What kind of flexibility do you have with the sheet?
Can you ensure that the values are sorted in ascending order?
Can you add row numbers?

I did this for A2:B45 ::
A B
6.002
11.753
17.504
23.255
29.006
35.007
40.758
46.509
52.2610
58.0011
64.0012
69.7513
75.5014
81.5015
87.0016
93.0017
98.0018
104.7519
110.5020
116.2621
122.0022
128.0023
133.7524
139.5025
145.2526
151.0027
157.0028
162.7529
168.5030
174.6031
180.0032
186.0033
192.0034
197.7535
203.5036
209.2537
215.0038
221.0039
226.7540
232.5041
238.2542
244.0043
250.0044
255.7545

(I used =ROW(A2) in column B so that it was more flexible)

Next, in D5, I put:
=OFFSET(INDIRECT(ADDRESS(VLOOKUP(C5,A2:V45,2,TRUE),1)),1,0)
This uses
VLookup to find the next LOWER number ("TRUE" enables this)
I used ADDRESS to return the cell  address.
I used INDIRECT to ensure that it used the ADDRESS instead of the VALUE at the
address
I used Offset to move to the next row (1 row, 0 columns) and returned the value
there.

So, in C5, I put the number 55.
In D5, it returns 58.

is this even close to what you were looking for?

If the numbers are not in order, I can write a function  that can loop through
the values and return the next greater value, but it requires the use of VBA
rather then Excel functions.