Presenting a value based on number or text in cell - excel

Question

I have a list of 4 values in Sheet1 and 4 values in Sheet2.
In Sheet3 I will combine a random selection of these numbers and return the value in a column. (edit: no random selection from Excel, its a part picked from a bucket)
(A fifth column in Sheet3 will be used to do calculations with ValueS1 and ValueS2)
Sheet1
NumberS1
ValueS1
1
17.10
2
17.20
3
17.12
4
17.15
Sheet2
NumberS2
ValueS2
1
16.10
2
16.20
3
16.12
4
16.15
Sheet3
NumberS1
NumberS2
ValueS1
ValueS2
1
3
17.10
16.12
2
2
17.20
16.20
4
1
17.15
16.10
3
4
17.12
16.15
What kind of function can give the desired return?
I have looked into examples using "Indirect" but cannot see how they will solve my problem.

Answer 1

for the randomization: =ROUNDUP(RAND()*4,0)
rand() gives you a number between 0 and 1, so rand()*4 gives you a number between 0 and 4.
roundup(x,y) round up the number x with y digits you want to round the number up to (in our case 0).
for import the right number from sheet 1 or 2: =VLOOKUP(A1,Sheet1!A1:B2,2,0)
A1 - The value you look for in sheet 1 or 2.
Sheet1!A1:B4 - The array he look for your value on the firs column, always on the first column.
2 - The column you want to import the value from. (because we write an array of tow columns. we can write here only 1 or 2)
0 - it's an Optionally index (0 or 1). o is if you want an exact match of the return value.

Answer 2

Regular Lookup could do:
=LOOKUP(A2:A5,Sheet1!A2:A5,Sheet1!B2:B5) in Sheet3!C2
And
=LOOKUP(B2:B5,Sheet2!A2:A5,Sheet2!B2:B5) in Sheet3!D2
Note that LOOKUP will give the result to the closest match smaller than the search value.
Or VLOOKUP:
=VLOOKUP(A2:A5,Sheet1!A2:B5,2,0) / =VLOOKUP(B2:B5,Sheet2!A2:B5,2,0)
VLOOKUP will error if the value is not found (the way used above). It uses arguments like this:
=VLOOKUP(What you want to look up, where you want to look for it, the column number in the range containing the value to return, return an Approximate or Exact match – indicated as 1/TRUE, or 0/FALSE)
Office 365 has XLOOKUP which combines the logic of the two above and some more:
=XLOOKUP(A2:A5,Sheet1!A2:A5,Sheet1!B2:B5,"value not found",0)
XLOOKUP uses the following arguments:
=XLOOKUP(lookup_value, lookup_array, return_array, [if_not_found], [match_mode], [search_mode])