Pfthb

I need to make many of these. If it s possible numbers to be aligned right. How to do that?

A no-package approach for three term or higher sums as well.

documentclassarticle

newcommandshowsum[2][c]%
 $edeforiginalplusmathcodethemathcode`+%
 begingrouplccode`~=`+ lowercaseendgroupdef~\&%
 mathcode`+ "8000
 beginarray[#1]@r@;r@
 mathcharoriginalplusmathcode& #2 \
 hline
 & thenumexpr#2relax
 endarray%
 $%
 

begindocument

Xquad % to show the baseline
showsum12345 + 6543quad
showsum521725 + 256814quad
showsum523057 + 6743quad
showsum[t]57208+6207quad
showsum[b]57208+6207+12095quad
X

enddocument

The X are here to indicate baseline. (plagiarized from @egreg)

Variant display:

documentclassarticle

newcommandshowsum[2][c]%
 $edeforiginalplusmathcodethemathcode`+%
 begingrouplccode`~=`+ lowercaseendgroupdef~\mathcharoriginalplusmathcode&%
 mathcode`+ "8000
 beginarray[#1]@r@;r@
 & #2 \
 hline
 =& thenumexpr#2relax
 endarray%
 $%
 

begindocument

Xquad % to show the baseline
showsum12345 + 6543quad
showsum521725 + 256814quad
showsum523057 + 6743quad
showsum[t]57208+6207+77777quad
showsum[b]57208+6207+12095+33333quad
X

enddocument

We can also sum negative integers:

documentclassarticle

newcommandshowsum[2][c]%
 $edeforiginalplusmathcodethemathcode`+%
 begingrouplccode`~=`+ lowercaseendgroupdef~\mathcharoriginalplusmathcode&%
 edeforiginalminusmathcodethemathcode`-%
 begingrouplccode`~=`- lowercaseendgroupdef~\mathcharoriginalminusmathcode&%
 mathcode`+ "8000
 mathcode`- "8000
 beginarray[#1]@r@;r@
 & #2 \
 hline
 =& thenumexpr#2relax
 endarray%
 $%
 

begindocument

Xquad % to show the baseline
showsum12345 - 6543quad
showsum521725 + 256814quad
showsum523057 - 6743quad
showsum[t]57208-6207+77777quad
showsum[b]57208-6207+12095-33333quad
X

enddocument

(there was a missing % after the final $ in all three showsum, fixed now but images not updated)

The code below defines a macro, Summation, that accepts a comma separated list of integers such as

 Summation12345, 6543
 Summation521725, 256814
 Summation523057, 6743
 Summation57208,6207
 Summation[b]57208,6207,12095

The macro then adds the integers in a table, as in the OP. The commands above give the output:

There is an optional first argument that becomes the positioning optional argument in the tabular environment (by default, t is used). I haven't really checked, but it is likely ro break with large integers.

All of the integers are printed using the num command from the siunitx package, so their formatting can be customised using siunitx. for example, by adding

sisetupgroup-separator=,,group-four-digits

the numbers will have a comma separating the thousands, millions, ... etc. so that the output becomes

The code is an exercise in using LaTeX3:

documentclassarticle
usepackagexparse
usepackagesiunitx

ExplSyntaxOn
clist_new:N l_int_clist
int_new:N g_total_int
tl_new:N g_summation_tl
NewDocumentCommandSummation Ot m
 clist_set:Nn l_int_clist #2
 int_zero:N g_total_int
 tl_clear:N g_summation_tl
 clist_map_inline:Nn l_int_clist 
 int_gadd:Nn g_total_int ##1
 tl_gput_right:No g_summation_tl & num##1\
 
 begintabular[#1]r@spacer
 + tl_use:N g_summation_tl cline2-2
 &numint_use:N g_total_int
 endtabular

ExplSyntaxOff

begindocument

 Summation12345, 6543
 Summation521725, 256814
 Summation523057, 6743
 Summation57208,6207
 Summation[b]57208,6207,12095

enddocument

As noted in Latex3 inline mapping produces extra row in tabular, it is necessary to construct the table as a token list because otherwise hrule will complain.

Let TeX do the calculations

documentclassarticle
usepackagexparse

ExplSyntaxOn
NewDocumentCommandshowsumOcm
 
 ensuremath
 
 simeon_showsum:nn #1 #2 
 
 

seq_new:N l__simeon_showsum_seq

cs_new_protected:Nn simeon_showsum:nn
 
 seq_set_split:Nnn l__simeon_showsum_seq + #2 
 beginarray[#1]@r@;r@
 + & seq_use:Nn l__simeon_showsum_seq \ & \
 hline
 & int_eval:n #2 
 endarray
 
ExplSyntaxOff

begindocument

Xquad % to show the baseline
showsum12345 + 6543quad
showsum521725 + 256814quad
showsum523057 + 6743quad
showsum[t]57208+6207quad
showsum[b]57208+6207+12095quad
X

enddocument

Here's a LuaLaTeX-based solution. The macro mysum takes two mandatory arguments -- the numbers to be summed -- and one optional argument, which determines how the array environment should be placed vertically relative to the math baseline: centered (the default), top-aligned, or bottom-aligned. (If an optional argument is set, it must be listed first and enclosed in square brackets, per the usual LaTeX macro syntax rules.)

documentclassarticle
usepackagebooktabs % for "midrule" macro
newcommandmysum[3][c]%
 beginarray[#1]@r@
 #2 \ +: #3 \ midrule directluatex.sprint(#2+#3)
 endarray
usepackagenewtxtext,newtxmath % optional (Times Roman text and math fonts)
begindocument
[
mysum123456543 qquad
mysum511725256814 qquad
mysum[b]5230576743 qquad
mysum[t]572086207
]
enddocument

Addendum to allow for an arbitrary number of summands rather than exactly two summands. The preceding code dealt with the case provided in the original query, which involved exactly two terms in the summation. The following solution, which is still LuaLaTeX-based, allows for an arbitrary number of summarnds. It works as follows:

• The LaTeX macro mysum takes one optional argument (the vertical placement indicator, see above) and one mandatory argument: a string of comma-separated numbers. Whitespace is allowed inside the string. Thus, mysum12345,6543, mysum12345, 6543, mysum 12345 , 6543 , and mysum12345,6543 , are all equally valid -- and produce the same output, viz., the number 18888.




• The mysum macro performs the following tasks: It sets up an array environment, calls the Lua function perform_summation to perform most of the actual work, and terminates the array environment.




• The perform_summation Lua function begins by splitting the comma-delimited string of numbers into a Lua table, using , as the separator. (The auxiliary function that performs the splitting was obtained from stackoverflow.) perform_summation then iterates over the table entries to (a) compute the running subtotal of the entries and (b) print out each entry on a separate row. Finally, the Lua function prints the value of the sum of the entries.

The 3 "-" symbols located at the left-hand and right-hand edges of the following screenshot merely serve to indicate the location of the math axis.

documentclassarticle
usepackagenewtxtext,newtxmath % optional: Times Roman text and math fonts
usepackagebooktabs % for "midrule" macro
usepackageluacode % for "luacode" environment

%% Lua-side code:
beginluacode

-- The following code is from https://stackoverflow.com/a/19263313:
function string:split( inSplitPattern )
 outResults = 
 local theStart = 1
 local theSplitStart, theSplitEnd = string.find( self, inSplitPattern, theStart )
 while theSplitStart do
 table.insert( outResults, string.sub( self, theStart, theSplitStart-1 ) )
 theStart = theSplitEnd + 1
 theSplitStart, theSplitEnd = string.find( self, inSplitPattern, theStart )
 end
 table.insert( outResults, string.sub( self, theStart ) )
 return outResults
end

function perform_summation ( s )
 t = s:split(",")
 sum = 0 -- initialize "sum" variable
 tex.sprint ( "+\:" ) -- print the "+" symbol
 for i=1,#t do
 sum = sum+t[i]
 tex.sprint ( t[i] .. "\\" )
 end
 tex.sprint ( "\midrule" .. sum )
end

endluacode

%% LaTeX-side code:
newcommandmysum[2][c]%
 beginarray[#1]@r@
 directluaperform_summation("#2")
 endarray

begindocument
[
---quad % indicate math axis
mysum12345,6543 qquad
mysum1234567891234,9876543219877 qquad
mysum1,2,3,4 qquad
mysum[t] 57208 , 6207 , 12095 qquad
mysum[b]12345,67890
quad--- % indicate math axis
]
enddocument