4 * 0.4 * 0.04 * 0.004 = _________?

A. 0.0256
B. 0.00256
C. 0.000256
D. 0.0000256

Explanation:

4 * 0.4 * 0.04 * 0.004 => 4 * (4/10) * (4/100) * (4/1000) = (256/1000000) = 0.000256