This is a really long and easy subtraction problem.
there are 11 digits in first number 76582948858 as well as second number 100000000000.
So this makes subtraction even more simple.
we have all the zeros excepts for the first place in second number.
We know that if we subtract any number from zero the number remains same.
a-0 = a
So that leaves us with just first place 7 and 1 , subtracting 7-1 gives us 6
rest all digits are unchanged.
so 76582948858-10000000000 =66582948858