Arithmetic

Fractions to Percent and Back · X percent of y — flip and multiply · Percent of percent: multiply, never add · What percent is: pick the right base · Percent Error: Divide by the Truth · Successive fractions of remainder

Successive change: multiply, never add · Reverse Percentage: Undoing a Rise · Area and Volume: Multiply the Factors · Price consumption compensation · Percent points vs percent · Income, Expenditure, Savings

Election votes · Marks pass fail · Population growth, year by year · Least Group Size: Whole People Only · Mixtures: fix what does not change · Weighted percent change

CP, SP and profit percent · Profit on SP vs profit on CP · Same SP, 20% on CP vs 20% on SP · CP of n equals SP of m · Profit equals price of k items · Rate per unit buy sell · Two prices: gain vs loss · SP difference to CP · When Profit % Equals the Cost Price

Chain of transactions · Overheads and tax · CP and SP Both Change · Break-even: Fixed + Variable Cost

Markup then Discount: One Line · Successive Discounts: Which Scheme Wins? · Discount to Get Target Profit · One Discount Instead of Two · Buy 2 Get 1 Free — Real Discount? · Discount Up, Profit Down · Markup vs Discount: The One-Line Rule · Price Cut, Volumes Up: Profit or Not?

Part at Profit, Part at Loss · Overall Percent From Two Items · False Weights at Cost Price · Dishonest dealer · Same SP, Gain and Loss · Two Items, Two Scenarios · Adulteration: Water in the Milk · Damaged Stock: Price for What's Left

SI: One Formula, Four Ways · Two parts two rates · Time to multiply · Rate from two amounts · Same Sum, Higher Rate: Find P Fast · Rate equals time · Staggered deposits, rising rates · SI Repayment Instalments

Basic CI · Half yearly quarterly · CI SI difference · Time to multiply k times · Instalments partial payment · Increasing yearly deposits · Two schemes split · CI to SI relation · Rate from successive amounts · Equal amounts split

Depreciation · Population growth CI · Percent change in value

Combining ratios · Ratio with integer constraint · Change in ratio after event · Coins denominations · Three way ratio from pairs · Dividing in ratio · Equal fractional parts · Expression from ratio · Numbers in ratio · Ratio linear system · Income expenditure savings · Ratio with percent change · Ratio properties · Leaps speed ratio

Direct inverse variation · Joint variation · Componendo dividendo · K method · Mean proportional · Partly fixed partly variable · Value of broken pieces

Time weighted capital · When did partner join · Profit share with salary · Capital changes midway · Capital from profit share

Linear age relations · Age ratio past future · Sum of ages · Quadratic age relations

Basic average · Add remove member · Weighted average · Consecutive numbers average · Overlapping group averages · Uniform change · Correction of wrong entry · Size biased average

Maximise one value given mean · Minimise one value given mean · Max difference given mean · Distinct integers mean constraint

Two mixture rule · Water addition concentration · Replacement repeated · Alloy swapped ratios · Three mixtures · Mixture with profit · Remove and add component

Individual combined LCM · Efficiency ratio · Alternate days · Leaving midway · Average completion time · Men days hours · Partial work rate · Pairwise combined · Quadratic times · Sequential portions · Rate change · Group equivalence · Workforce change · Workforce AP · Provisions

Fill and drain · Two outlets · Leak time · Pipes opened in turns · Pipe closed midway · Partial tank · Identical pipes · Capacity litres · Flow diameter

Wage share by work · Wage share by days

Average speed · Speed change time change · Early late arrival · Gear speed segments · Unit conversion · Delayed start catch up · Stoppage time · Proportionality speed time · Part journey modes · Accident mid journey · Walk ride round trip

Trains crossing · Trains opposite · Meeting point · Overtaking delayed start · Speed ratio from meeting times · To and fro meetings · Scheduled trains crossing · Chase and catch · Sound interval · Escalator · Train passes walkers · Bus frequency · Approach vs overtake times

Linear race beat by · Circular track meetings · Circular overtakes · Race with head start · Diametrically opposite start

Upstream downstream · Still water stream speed · Time ratio up down · Alternating up down position · Round trip total time · Floating object · Two boats relative

Angle between hands · Hands coincide opposite · Clock gain loss · Clock striking

True discount · Bankers discount · Bankers gain · Present worth · TD SI relation

Income from stock · Brokerage · Market value face value · Dividend yield · Stock switch

Odd days · Day of week · Leap year rules · Same calendar year · Weekday count

Missing term · Wrong term · Pattern identification