(i) To convert an ANNUAL trend equation into a monthly trend equation : Divide a by 12, BX, by 12 12 (or 144), cX², by 12 × 12 × 12 (or 1728) and so on.Explanation:By conversion of a trend equation, we mean the change of trend equation formulated on one type of time basis into a trend equation on another type of time basis. Thus, if a trend equation of YEARLY period is TRANSFORMED into a trend equation of monthly or quarterly period, or vice versa, it will be called conversion of a trend equation.Methods of Conversion.The following methods are to be ADOPTED for converting a given trend equation into a required trend equation:(i) To convert an annual trend equation into a monthly trend equation : Divide a by 12, bX, by 12 12 (or 144), cX², by 12 × 12 × 12 (or 1728) and so on.(ii) To convert a monthly trend equation into an annual trend equation. Multiply a by 12, bX by 12 × 12 × 12 (or 1728) and so on.(iii) To convert an annual trend equation into a Quarterly trend equation :Divide a by 4, bX by 4 × 12 (or 48), cX², by 4 × 12 × 12 (or 576) and so on.(iv) To convert a quarterly trend equation into an annual trend equation :Multiply a by 4, bX by 4 × 12 and cX², by 4 × 12 × 12 and so on.Example is in above image