1. Find mistakes in the following calculations and calculate correctly.

    1) 
    2) 

    3) 

    4) 

    5) 

2. Find the common factor of the following numeral-pairs.

    12 ja 32                15 ja 20                60 ja 140            45 ja 125

3. Compute in your head.

1)         2)         3) 

4. The length of a rectangular garden is 87 ½ m, the width is 20 1/5m shorter than the length. How long is the fence surrounding the garden?