What is 3.14 x 4?
Don't get cared by the decimal, it's just a point. It means:
divide by 10^n where n is the number of digits after the
decimal.
So in this case, 3.14 means 314 / 10^2 = 314 / 100
so you are actually doing this 314/100 x 4 = 314 x 1/100 x 4.
Multiplication is commutative so you might as well do 4 x 314, then
divide by 100.
So you should get 1256 / 100. To divide by 100, recall what
decimal means, it's simply 12.56 :D