The phloem tissues in plants are responsible for the movement of sugars from the leaves to different areas of the plant. This allow all of the plant to have the necessary energy to carry out its cellular activities. Phloem is just one part of the plant's vascular system, which is a larger organ system that moves materials through out the plant. What animal organ system is most similar to the vascular system of a plant?

Adding the numbers 26.45 and 2.55 normally will give an answer of 29. The rule on significant figures on operations involving either subtraction or addition states that the final answer should be rounded to the least number of decimal places among the addends. In the example above, the least number of decimal places is 2. The answer of the addition should be 29.00 which has four significant figures. 

Therefore, the answer is four.