Quant Formula Sheet

Percentages

• To increase X by P% → X × (1 + P/100)
• To decrease X by P% → X × (1 − P/100)
• Successive percentage change of a% and b% → a + b + (ab/100)

Time & Work

• If A does a job in x days, A’s 1-day work = 1/x
• Combined 1-day work of A and B = 1/x + 1/y
• Total time together = xy / (x + y)

Averages & Ratios

• Average = Sum of values ÷ Number of values
• If average changes when one value is replaced, difference = (new average − old average) × total count
• Ratio a:b, if total is T → parts are (a/(a+b))×T and (b/(a+b))×T

Who this is for

Candidates who’ve already covered these topics and want a fast pre-exam recall page, not a first-time explanation.