To answer your question: What is 4% of 68 billion, you can think of it as an algebraic sentence being:
X=0.04*68000000000
Multiply 68 billion by 4% and you get the what or x, is equal to 2,720,000,000 or 2.72 billion
Easier trick to avoid all the zeros, call it 68 and multiply by 4%, that is 2.72, add the word billion.
Hope this helps :-)
