Here is a multiplication involving two 16-digit numbers:

3851902343886132x5221791683705111
The 32-digit product is 20 113 831 625 748 8_8 690 240 050 420 652
What is the missing digit in the product?

2 answers

search "full precision calculator"
2
Any online calculator can supply this.
Not sure why this problem would be assigned. Do students still have to do tedious multiplication assignments by hand?