Learn to find the value of one unit first, then scale it up or down to solve everyday problems — including how long a job takes.
The unitary method means finding the value of a single unit first, then multiplying to find the value of any number of units. This works for cost, distance, speed, and many other real-world situations.
If 5 pens cost ₹75, what is the cost of 8 pens?
1 pen = ₹75 ÷ 5 = ₹15, so 8 pens = ₹15 × 8 = ₹120
A car travels 240 km in 4 hours. How far does it travel in 7 hours at the same speed?
1 hour = 240 ÷ 4 = 60 km, so 7 hours = 60 × 7 = 420 km
If a person can complete a job in a certain number of days, they complete 1/(number of days) of the job each day. Adding up daily work rates helps solve problems about people working together.
If a worker can finish a wall in 10 days, what fraction of the wall is completed in 1 day?
1/10 of the wall
If a worker completes 1/10 of a job in a day, how many days to complete 3/5 of the job?
3/5 ÷ 1/10 = 3/5 × 10 = 6 days
1. If 6 notebooks cost ₹90, what is the cost of 10 notebooks?
2. A machine produces 150 toys in 5 hours. How many toys in 8 hours?
3. A worker can complete a job in 12 days. What fraction is completed in 1 day?
4. If a tap fills 1/8 of a tank in an hour, how many hours to fill the whole tank?
5. If 4 workers can build a wall in 15 days, how many days would it take 1 worker alone (assuming the same work rate)?