Find the area in millimetres2 of a rectangular piece of steel 1800mm x 900mm 
The formula for calculating the area of a rectangle is
A = l x b
Substitute l and b with the length and breadth measurements of this rectangle
A = 1800 x 900
= 1620000
The answer for an area problem is given in square units
A = 1620000mm2
If the area is required in m2 convert the l and b measurements into metres before beginning the calculation
A = l x b
A = 1.8 x 0.9
A =1.62 m2