1 decimeter = 10/0cm
1 km (km) =1000m
1 ton = 1000 kg
Perimeter of rectangle = (length+width) *2
Circumference of a square = side length *4
1 min =60 seconds
(That's all the formulas in the last semester of Grade Three, a+b=b+a ... These algorithms were learned in the next semester of Grade Four)