Summarize the values from files

One of my process will create a file Market.txt with data like below.
Count Markt file
334936 /pdm/data001/P3_Quest_5HT_AMERGE.csv
2770787 /pdm/data001/P3_Quest_ARB_ATACAND.csv
1198143 /pdm/data001/P3_Quest_Bisp_ACTONEL.csv
3821864 /pdm/data001/P3_Quest_CONTRA_ALL_OTHER_CONTRA.csv
5014463 /pdm/data001/P3_Quest_Diab_ACTOSPLUS.csv

I will have another file Product.txt with data like below.
Marketname Products
5HT 13
ARB 11
Bisp 4
Contr 41
Diab 31
Now from first file market.txt i want to get the count of respective market and want to multiply with products which is Product.txt .Like that i want to get value from first file and want multiply with product for all markets and finally i want to summarize value for all the markets.
example
334936*13+2770787* 11+1198143* 4+3821864*41+5014463* 31=409560379929

Using shell script how to achive above one.

Note:In both files market names will be in same order.

Is that sum value is right?

 awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{print sum}' Market.txt Product.txt

i am getting result as 3.5177e+08.it is displaying wrong answer.

awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{OFMT="%20f";print sum}' Market.txt Product.txt

Its working ,Thanks for the Help but I am getting result as 351770174.000000 i want to display as 351770174.

 
awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{OFMT="%20f";print int(sum)}' Market.txt Product.txt

Or

awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{OFMT="%20d";print sum}' Market.txt Product.txt

i am getting different answer 1040187392.

---------- Post updated at 06:17 AM ---------- Previous update was at 05:57 AM ----------

i am getting different answer.

---------- Post updated at 07:49 AM ---------- Previous update was at 06:17 AM ----------

awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{OFMT="%20f";print int(sum)}' Market.txt Product.txt
answer:351770174.00000

awk 'NR==FNR{A[NR]=$1;next}
{sum+=($2*A[FNR])}END{OFMT="%20d";print sum}' Market.txt Product.txt
answer:1040187392

my expected result is 351770174
Please help on this.