Hi . how do i convert mm into sqmm .?

Question

fr eg: 450 x 200 mm = - sqmm

Answer 1

450 mm x 200 mm= 90000 sqmm
let me tell you that in this case you are converting the distance into area.
Single 400mm (say Length)& 200 mm (say Breadth) are the two dimensions in length and by multiplying both of them you will convert in area. If you want to conver it in Cubic mm, you need one more dimension, In this case we assume I mm, Then

450mm x 200mm x1mm = 90000 cu mm

Answer 2

If the object/picture measures 450mm across and 200mm vertically, just multiply the two numbers.

450x200 = 90 000 sq mm.

(9000sqcm/90sq metres)

I say "picture", because it must be a flat object or surface to have just the 2 measurements.