Use countif

=COUNTIF(Table2,A1)=1

where Table 2 is the table with missing numbers with absolute references
for instance $A$1:$E$5000 and A1 is the first cell in the complete table,
if you copy across and down the missing number will return FALSE

You can hightlight the cells using formatconditional formatting and formula
is,
note that you need a defined name if they are in different sheets (name the
table with missing numbers to for instance "MyTable" under insertnamedefine)
=COUNTIF(MyTable,A1)=1

Regards,

Peo Sjoblom

"kg1953" wrote:

Hi I have two tables both with approx. 5000 entries, Data Table A is correct
with 1-4999 but table two misses numbers out example 3500-3900 missing or
4000 -40006 missing how do I find out what numbers are missing by comparing
data from table A to the data in Table B? I have heard of lookup tables but
not sure how toi use these, any help much appreciated.