How can I calculate steel of slab?

How can I calculate steel of slab?

How can I calculate steel of slab?
Example: We have to find the steel quantity for the room , Which size is 5 m x 4 m .
Given Data :

Size of Room = 16.4 x 13.12 ft

Main bars diameter = d = 0.5 inch (12 mm).

Distribution bars diameter = d =0.4 inch (10mm).

Spacing of Main bars = c/c = 150 mm c/c or 0.49 ft or 5.9inches

Formula to find the No’s of ( M.B ) Main bars = 500 / 15 + 1= 34.33 say 35

Straight bar = 18

Bent up bars = 17 cranked bars to act against negative moment.

2) Spacing of Distribution bars = c/c = 20 cm c/c or 0.65 ft or 7.87 inches.

Formula to find the No’s of ( D.B ) Distribution bars = 400 / 20 + 1= 21 No’s

unit weight of steel or density is 7850 kg/m3.

or Weight of steel = D^2/162 kg/m.