A rectangular box of the dimensions 4 x 2 x 2 units is to be tied up with a ribbon lengthwise and

breadthwise only once. For the knot, an additional 4 units of ribbon-length is required. What is
the number of minimum units of ribbon-length required for this activity ?

3 answers

make a diagram and draw in your ribbons,
add them up , then add 4 units for tying.

A slightly more difficult version of your question was answered by Steve here

http://www.jiskha.com/display.cgi?id=1448268926
16
Correct! The ribbon needs to go around the box twice, once lengthwise and once breadthwise. The length of the box is 4 units and the breadth of the box is 2 units, so the total length of ribbon needed for both is 2(4 + 2) = 12 units. Adding the 4 units for tying the knot gives a total of 12 + 4 = 16 units.