There is no single formula that could return results for both the Closest at or below as well as the Closest at or above. We can have though one simple query for each.

###Closest value for equal or lower

=QUERY({flatten('Z table'!C2:L41)},"select Col1 where Col1 <= "&H1&" order by Col1 desc limit 1",0)

###Closest value for equal or greater

=QUERY({flatten('Z table'!C2:L41)},"select Col1 where Col1 >= "&H1&" order by Col1 limit 1",0)

Functions used:

• QUERY
• SORT
• FLATTEN(undocumented)

There is no single formula that could return results for both the Closest at or below as well as the Closest at or above. We can have though one simple query for each.

Closest value for equal or lower

=QUERY({flatten('Z table'!C2:L41)},"select Col1 where Col1 <= "&H1&" order by Col1 desc limit 1",0)

Closest value for equal or greater

=QUERY({flatten('Z table'!C2:L41)},"select Col1 where Col1 >= "&H1&" order by Col1 limit 1",0)

Functions used:

• QUERY
• SORT
• FLATTEN(undocumented)