这个真的不知道应该用高精还是FFT,所以...

来介绍几种自带高精的语言

Python3:

n = int(input())
for i in range(0, n):
    s = input().split()
    print (int(s[0]) * int(s[1]))

Python2:

n = int(raw_input())
for i in range(0, n):
    s = raw_input().split()
    print int(s[0]) * int(s[1])

Ruby:

n = gets.to_i
for i in 1..n do
    a, b = gets.split
    a, b = a.to_i, b.to_i
    puts a * b
end