Ivan wanted to cut small identical 4 cm by 3 cm rectangles from a rectangular cardboard measuring 30 cm by 20 cm. What is the maximum number of complete small rectangles Ivan could cut? (Note: Ivan could rotate the small rectangle.)
To have the maximum number of small rectangles, there should be no wastage of cardboard.  

When 20 is divided by 4, there is no remainder.  However, if 20 is divided by 3, there is a remainder.

When 30 is divided by 3, there is no remainder. However, if 30 is divided by 4, there is a remainder.

Number of small rectangles that can be cut breadthwise
= 20 ÷ 4
= 5

Number of small rectangles that can be cut lengthwise
= 30 ÷ 3
= 10

Number of small rectangles that Ivan could cut from the rectangular cardboard
= 5 x 10
= 50

Answer(s): 50