Faster Percentage Calculation

Shortcut tricks on boats and streams are one of the most important topics in exams. These are the formulas and examples on Boats and Streams (Cyclist and the wind or Swimmer and stream) questions. These examples will help you to better understand shortcut tricks on boats and streams questions.


There are multiple types of questions asked from these topics. The speed of the boat in still water and the speed of stream will give in questions, You have to find the time taken by boat to go upstream and downstream. .
The speed of the boat in up and down stream will give in question,  you need to find the average speed of the boat.
The speed of boat to go up or down the stream will give in question, you need to find speed of boat in still water and speed of stream.
The time taken by boat to reach a place in up and downstream will given in question, you need to find the distance to the place.

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Problems Type 1: .

A can finish work in X days. .

B can finish work in Y days.


Both can finish in Z days = (X*Y) / (X+Y). .


Problems Type 2: .

Both A and B together can do work in T days.

A can do this work in X days.


then, B can do it in Y days = (X*T) / (X-T) .


Problems Type 3: .

A can finish work in X days.

B can finish work in Y days.

C can finish work in Z days.


Together they can do work in T days = (X*Y*Z)/ [(X*Y)+(Y*Z)+(X*Z)] .


Problems Type 4: .

A can finish work in X days.

B can finish work in Y days.


A*X = B*Y.

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The quickest way to calculate percentages is to multiply numbers first and handle two decimal places later.

For example, 20% of 70 is 20 x 70 = 1400, so the answer is 14. .

70% of 20 is also 14.

To calculate the percentage of 72 or 29, then round up and down to the nearest multiple (70 and 30 respectively) to get a quick approx result.

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