Given expression is, 0.004 x 0.04 x 0.4 x 0.0004The multiplication value without decimal point = 4 x 4 x 4 x 4 = 256Sum of the number of decimal places in the given numbers = 3 + 2 + 1 + 4 = 10Now, in the product, the decimal point is marked off to obtain as many places of decimal.Then the answer is 0.0000000256.