For a homework assignment on significant digits, I have to find the number of significant digits in the number 0.40×103. I know that in scientific notation, the number of significant digits is equal to the number of digits in the stem. However, I've also learned that for a number to be in scientific notation, it must have a stem between 1 and 10. What is the rule for this situation? Is the number of Significant digits 2 or 3?