unit cost detailes of finished item standard cost not clear

ahmedba

Hi guys i have item ASI00H4000 his costing method is standard and unit cost is 200 and it is finished good item and this item has more bill of material as following :
No. Description Quantity per Unit of Measure
OPC Cement 48 KG average
AGG1 Aggregate 397 KG average
AGG2 Aggregate 283 KG average
AGG3 Aggregate 293 KG average
SN02 Sand 767 KG average
W1 Water 125 KG average
W2 Ice 50 KG average
ADM1 SP430R 10.08 LITER average
ADM2 RP264 1.1 LITER average
The item ASI00H4000 is finish good and contain all raw material's as above for 1 cubic meter
I open card to this item ASI00H4000 i see unit cost is 253.83752 and costing method standard
My questions is
1 - give me details of this value 253.83752
I make total to bill of materials but not come 253.83752 the value come is 188 it less from this value what the remaining value represent.
this value show also after i make adjust cost item entries to all raw materials and finish good item