'subtract' a range of numbers from another range

[excelNewbie22]

hi!

so i have a long list of 1000 shuffled numbers with duplicates (col a) ,
which always changing,
all from within a range of 1000-1500,
(example 1001,4050, 3182, 4992, 1002, 4050 and so on)

i want to exclude constantly the first 400,
with these 400, i want to delete the duplicates,
and let's say i left with 200 unique numbers (col b),
then 'subtract' these 200's from the 500 unique numbers of the range of 1000-1500,
and then display the remaining 300 in another column (col c)

now, i've already have a way to do it,
with sorting and filtering and condition formatting,
but since i'll need to do so lot's of times,
i wonder can it be done in a shorter way?
maybe with formulas? even several?

i thought something with unique function maybe?



p.s
the range and numbers are just examples,
the originals are different,
and assuming there will be a solution i'll modify it to my needs

 

[Fluff]

You originally said that column B was the result of the Unique function, therefore the formula I suggested uses that.

 

[excelNewbie22]

right!
it worked!
but only once... then try to save.... and it's stuck,
kill the app, start over, and keep stucking....

 

[Fluff]

Is this any better

=LET(b,BASE(SEQUENCE(8^4,,0),8,4)+1111,FILTER(b,ISNA(MATCH(b,B2#,0))))

 

[excelNewbie22]

it's doesn't stuck but also doesn't filter/subtract from col b, just give the all range from start to end

 

[Fluff]

Filter them out for me

Fluff.xlsm
	A	B	C
1	col a
2	1111	1111	1112
3	1113	1113	1114
4	1121	1121	1115
5	1123	1123	1116
6	1131	1131	1117
7	1118	1118	1122
8	1111	1320	1124
9	1123		1125
10	1131		1126
11	1320		1127
12			1128
13			1132
14			1133
15			1134
16			1135
17			1136
18			1137
19			1138
20			1141
Main

Cell Formulas
Range	Formula
B2:B8	B2	=UNIQUE(A2:A11)
C2:C4091	C2	=LET(b,BASE(SEQUENCE(8^4,,0),8,4)+1111,FILTER(b,ISNA(MATCH(b,B2#,0))))
Dynamic array formulas.

 

[excelNewbie22]

right again... i copied yours and it's works perfectly!
but when i do the same with my file nothing changing...
weird!

 

[Fluff]

Are you sure the numbers in col B are real numbers & not text?

 

[excelNewbie22]

you are onto something.... when i try changing one of them in col a manually it works, but only for the one change manually,
but when i copied the entire range to col a from the data file, the formula in col c don't work

so.... what do you mean by REAL numbers?

 

[Fluff]

I mean numbers rather than text.

 

[excelNewbie22]

yes, numbers only,
i tried copy some into here,
preview it,
then copy back,
and it worked,
why is that?