Binary conversion to significant decimal digits

Question

Question 1: Add 12_ten to 15_ten in binary and then subtract 12_ten from 15_ten in binary.
 
Question 2: Using 4-bit numbers to save space, multiply 3_ten x 4_ten in binary.
 
Question 3: Using a 4-bit version of the algorithm to save space, divide 5_ten by 3_ten in binary.
 
Question 4: Add 3.76_ten x 10⁰ to 3.45_ten x 10², assuming that we have three significant decimal digits. Round to the nearest decimal number with three significant decimal digits, first with guard and round digits, and then without them.