Shortcut Techniques
Work & Time · Study material
Shortcut Techniques – Work & Time
Shortcut techniques in Work & Time help candidates solve aptitude questions quickly and accurately in SSC, Banking, Railway, CDS, NDA, CAT, UPSC, and placement examinations.
Most Work & Time questions are based on:
- Efficiency of workers
- Combined work calculations
- Men-days-hours concepts
- Pipes and cisterns
- Alternate working patterns
- Work distribution and productivity
Using shortcut techniques reduces lengthy calculations and improves problem-solving speed significantly.
Why Learn Work & Time Shortcuts?
- Improves calculation speed in exams.
- Reduces complicated fraction calculations.
- Useful in Time & Work and Pipes & Cisterns.
- Helps solve combined work problems quickly.
- Improves logical and analytical thinking.
Shortcut #1: Assume Total Work as LCM
Instead of assuming total work as 1, assume:
Total Work = LCM of Given Days
Example:
A completes work in 12 days
B completes work in 18 days
LCM = 36
A's efficiency:
= 36/12 = 3 units
B's efficiency:
= 36/18 = 2 units
✔ LCM method removes fractions and speeds up calculations.
Shortcut #2: Combined Work Formula
If:
- A completes work in x days
- B completes work in y days
Then together:
Total Days = xy / (x + y)
Example:
A = 12 days
B = 18 days
Together:
= (12 × 18) / (12 + 18)
= 216/30
= 7.2 days
Shortcut #3: Three Workers Formula
If:
- A completes work in x days
- B completes work in y days
- C completes work in z days
Then together:
Days = xyz / (xy + yz + zx)
Shortcut #4: Efficiency Ratio Trick
Efficiency is inversely proportional to time.
Efficiency Ratio = Time Ratio (Reverse)
Example:
A takes 10 days
B takes 15 days
Efficiency ratio:
= 15 : 10
= 3 : 2
Shortcut #5: One Day Work Shortcut
If a person completes work in n days:
One Day's Work = 1/n
Use this directly in combined work questions.
Shortcut #6: Men-Days-Hours Formula
For men-days-hours problems:
M × D × H / W = Constant
Where:
- M = Men
- D = Days
- H = Hours
- W = Work
Shortcut #7: More Men Less Time Rule
Men and time are inversely proportional.
More Men → Less Time
Example:
10 men complete work in 20 days.
20 men will complete in:
= 10 days
Shortcut #8: Work Efficiency Shortcut
If A is n times more efficient than B:
Time Ratio = 1 : n
Example:
A is 3 times as efficient as B.
If B takes 30 days:
A takes:
= 30/3
= 10 days
Shortcut #9: Alternate Day Work Trick
When workers work alternately:
- Find work done in one cycle.
- Calculate number of complete cycles.
- Find remaining work separately.
✔ Alternate work problems become easier using cycle method.
Shortcut #10: Pipes and Cisterns Shortcut
Pipes and cisterns follow Work & Time concepts.
Filling Pipe = Positive Work
Emptying Pipe = Negative Work
Shortcut #11: Quick Combined Efficiency Method
Add efficiencies directly instead of adding times.
Total Efficiency = Sum of Individual Efficiencies
Example:
A = 1/10
B = 1/15
Together:
= 1/10 + 1/15
= 1/6
Together they finish in:
= 6 days
Shortcut #12: Reverse Time Method
If efficiency doubles:
Time becomes half.
If efficiency triples:
Time becomes one-third.
Shortcut #13: Fraction Cancellation Trick
Cancel common factors before multiplication.
(12 × 18) / (12 + 18)
= 216/30
= 36/5
This reduces calculation time significantly.
Shortcut #14: Direct Work Formula
For quick calculations:
Work = Efficiency × Time
Use directly in productivity questions.
Shortcut #15: Work Ratio Trick
If:
- A's efficiency = 3 units/day
- B's efficiency = 2 units/day
Then:
Work Ratio = 3 : 2
Use this for wage-sharing problems.
Shortcut #16: Total Work Units Method
Assume total work as:
- LCM of given days
- 100 units
- Simple divisible number
This simplifies calculations greatly.
Shortcut #17: Wage Distribution Shortcut
Wages are distributed according to:
Ratio of Work Done
More efficient worker receives higher wages.
Shortcut #18: Work Completion Shortcut
If two workers together complete work in x days:
Total Work = x × Combined Efficiency
Use this in alternate and partial work questions.
Shortcut #19: Remaining Work Technique
For incomplete work problems:
- Calculate completed work first.
- Subtract from total work.
- Find remaining time separately.
Shortcut #20: Memory Formula Table
| Concept | Formula |
|---|---|
| One Day Work | 1/n |
| Combined Work | 1/x + 1/y |
| Two Persons Together | xy/(x+y) |
| Three Persons Together | xyz/(xy+yz+zx) |
| Efficiency Ratio | Reverse of Time Ratio |
| MDH Formula | MDH/W = Constant |
Important Exam Tips
- Use LCM method to avoid fractions.
- Memorize combined work formulas.
- Practice alternate work questions regularly.
- Remember efficiency-time inverse relation.
- Use cycle method in repetitive work problems.
- Simplify ratios carefully.
- Verify final calculations properly.
Shortcut techniques in Work & Time help candidates improve calculation speed, reduce lengthy computations, and solve aptitude questions efficiently in competitive examinations.