How many significant does 0.00400 have?

What is the value of the digit 3 in the number 13? What was the root cause of tension between these two superpowers? Does one positive plus one negative equal a positive? What is 27 over 3 simplified? What is the estimate for 20 and 50? What percentage is one in a half? What is the name of a shape bounded by ordered pairs? How many lbs is it to make a ton? What is the perimeter of a rectangle 4.5 m x 1.5 m? What capital letters have reflectional symmetry? How long will it take mail to travel 800 miles? How any combinations in using all 10 numbers can you get to 6 places? What do the numbers on the bottom of your hummel mean? What does theoretical expected value mean? The highest point on the fir compound word long e? How many dimes are in 5 dollar roll? Whats the use of using ampersand in PHP? What percent is 180 of 200? What is the square root of 45 rounded to the nearest tenth? Can chatterbox frs x2 talk to gmrs x1?