Cost Price : The price at which an article is purchased, is called its cost price,
abbreviated as C.P. Selling Price : The price at which an article is sold, is called its selling price,
abbreviated as S.P. 1 Profit or Gain : If S.P. is greater than CR, the seller is said to have a profit
or gain. Loss : If S.P. is less than C.P., the seller is said to have incurred a loss.

Gain = (S.P.) - (C.P.)

Loss = (C.P.) - (S.P.)

Loss or gain is always reckoned on C.P.

_{Gain% =}^{Gain X 100 } ^{C.P.}

_{Loss% =}^{Loss X 100 } ^{C.P.}

_{S.P. =}^{100 + Gain% }_{ X C.P.} ^{100}

_{S.P. =}^{100 - Loss% }_{ X C.P.} ^{100}

_{C.P. =}^{ 100 }_{ X S.P.} ^{100 + Gain%}

_{C.P. =}^{ 100 }_{ X S.P.} ^{100 - Loss%}

If an article is sad at a gain of say, 35%, then S.P. = 135% of C.P.

If an article is sold at a loss of say, 35%, then S.P. = 65% of C.P.

When a person sells two similar items, one at a gain of say, x%, and the other
at a loss of x%, then the seller always incurs a loss given by :
Loss% =
(^{Common Loss and Gain%}/_{10})^{2}
= (^{x}/_{10})^{2}

If a trader professes to sell his goods at cost price, but uses false weights, then _{Gain% =}^{ Error }_{ X 100 %} ^{(True Value) - (Error)}