Write 0.001742 in scientific notation.

1.742 x 10^-3

This is because you have to move the decimal so there is no non zero digits left in the decimal point and if the number of decimal places you move will be the exponent on the "10". If you move the decimal to the right it will be a negative and if you move it to the left it will be a positive.

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents