If I just use the numbers you have given above, this is how I see it. I'd be happy for you to correct me if I'm off the path here.

Using the tin at 1.8kg and providing 80% solids, as per your assumption, gives 1.44 kg solids plus 1.0 kg sugars, M.E. = 2.44 kg.

Total volume of liquid was 22.5 litres.

Your little table gives SG = 1.041644 and oP = 10.41089

The first equation SG = (4*oP)/1000 + 1 is the relationship between or conversion from Specific Gravity to degrees Plato.

= (4 * 10.41089)/1000 + 1

= 41.644 / 1000 + 1

= 0.041644 + 1

= 1.041644

This works but the factor of 4 inside the brackets is missing from the second equation.

M.E. = V * SG * oP

= 22.5 * 0.041644 * 10.41089

= 9.7548998211 kg

This answer is incorrect until I divide by the missing factor of 4 giving;

M.E. = 2.438724955275 kg, which rounded to 2 decimal places is the assumed mass in volume of 2.44kg.

So shouldn't the second equation be M.E. = (V * (SG -1) * oP) / 4. You could put the divide by 4 anywhere on this side, and to make it more related to the first equation it would be M.E. = V * (SG-1)/4 * oP

or we could write the equation as 4 M.E. = V * (SG - 1) * oP

Note: If you use SG as 1.041644 in the original equation you get and answer of 243.9999248211 kg, or 244 kg rounded which is order of magnitude out by 100 times. M.E. = 22.5 * 1.041644 * 10.41089

= 243.9999248211