We've to divide 0.256 by 100000. There are 5 zeros in 100000. So we have to move the decimal 5 places to the left in 0.256 for dividing it by 100000.
⇒0.256÷100000=0.00000256
Now, We've to represent the result in standard form.
0.00000256=2.56×10−6
Hence, 0.00000256 will be represented as 2.56×10−6 in the standard form.