Rule  Description 

1  If Marked Price = (MP) Selling Price = (SP) Then,
Note: Any kind of Discount is calculated only on Marked Price (MP) and not on Selling Price (SP) or Cost Price (CP). 
2  If article is sold on D% discount, then

3  When successive Discounts \[D_1, D_2, D_3,\] so on, are given then \[SP=MP\left(\frac{100D_1}{100}\right)\left(\frac{100D_2}{100}\right)\left(\frac{100D_3}{100}\right)\] 
4  If \[D_1, D_2, D_3,\] are successive discounts, then equivalent discount/overall discount is (in percentage) \[100\left[\left(\frac{100D_1}{100}\right)\left(\frac{100D_2}{100}\right)\left(\frac{100D_3}{100}\right)\times100\right]\] 
5  When two successive disounts \[(D_1, D_2)\] are given, then overall discount = \[\left(D_1+D_2\frac{D_1D_2}{100}\right)\%\] 
6  If r% of profit or loss occur after giving D% discount on Marked Price (MP), then \[\frac{MP}{CP}=\frac{100\pm r}{100D}\] (positive sign (+) for profit and negative () for loss) 
7  ‘y’ articles (quantity/number) are given free on purchasing ‘x’ articles. Then, Discount % = \[\frac{y\times100}{x+y}\] 
8  A tradesman marks his goods r% above his cost price. If he allows his customers a discount of r_{1}% on the marked price. Then his profit or loss per cent is \[\frac{r\times\left(100r_1\right)}{100}r_1\] (positive sign (+) for profit and negative () for loss) 
9  \[\left(\frac{r+R}{100r}\times100\right)\%\] more than its cost price.The Marked Price (MP) of an article is fixed in such a way that after allowing a discount of r% a profit of R% is obtained. Then the marked price of the article is \[\left(\frac{r+R}{100r}\times100\right)\%\] more than its cost price. 