4,000,000 x 5 would equal 20,000,000. The way to solve these are simple without a calculator.
Simply take the first numbers on the right that aren't 0's. [4]
Next, with the 0's ignored, multiply by whatever number it's asking for. [4x5]
Now that have an answer, bring the 0's back to the answer you found. [(20)(000,000)]