Write each number in scientific notation
6. 0.4 (21 zeros after the decimal place)

0.4x10'20

Step-by-step explanation:

for the scientific notation u need to move the decimal to make a small number.

0.0000000000000000000004 ---> 0.4

move the decimal 20 spaces to the right

(formula:(number times 10(expontent 'the moved spaces'))

0.4x10'20

(the 20 is the expontent)

the answer would be c