It takes Randy and Sam 12 hours to complete a  science project. If Randy works alone on the same project for 16 hours and let Sam take over, Sam needs another 7 hours to complete it. How long does it take Sam to complete the science project alone ?

The grass on a ranch grows at a constant rate every week.

240 sheep will eat up the grass in 6 weeks

200 sheep will eat up the grass in 10 weeks

For how many weeks can the pasture sustain a herd of 190 sheep ?

Mr Kaufman needs a total of 24 hours to harvest his crops. If his son chips in for 6 hours, they will finish the harvesting in 16 hours. How many hours will his son take to harvest the crops all by himself ?

Randy and Steven can finish painting a farmhouse in 6 days. It takes Steve and Tim 9 days to do the same task. Randy and Tim take 12 days to do the same task. How many days will it take if the three boys do the painting together ?

If Hoses A and B are turned on at the same time, they will take 9 hours to fill a swimming pool. It takes Hoses A and C 12 hours to fill the same pool. Hoses B and C will take 18 hours to do the same job. How many hours will it take to fill the pool if all the three hoses are turned on at the same time ?

A piece of pasture is growing at a constant rate every day.

It is able to sustain a herd of 100 cows for 20 days

It is able to feed a herd of 150 cows for 10 days.

For how many days is the piece of pasture able to feed 250 cows ?

How many different ways are there to form a 3-digit number if the three numbers are chosen from 1, 2, 3, 4 and 5 ?

The sum of the digits of a 2-digit number is 9. How many such numbers are there ?

Computer 100 – 96 + 94 – 90+…+ 46 – 42 + 40 – 36

The ones  digit of a 6-digit number is 7. The product of this 6-digit number by 5 is a 6-digit number that begins with 7. The rest of the 5 digits of the product equal the first 5 digits of the original number. Find the 6-digit number.

Palinddromes are numbers that read the same forward and backwards. Examples of palinddromes are 12321 and 24642. How many 5-digit palinddromes are even numbers ?

David misread the ones digit of a number A and the product of A and B became 407. Sophia misread the tens digit of A and the product of A and B became 451. Find the value of A x B

The sum of two numbers is 88. The product of the two numbers is 1612. What are the two numbers ?

Find the value of the following:

20082009 x 20092008 – 20082008 x 20092009

The sum of the digits of a 3-digit number is 18. The tens digit is 1 more than the ones digit. If the hundreds digit and the ones digits are swapped, the difference between the new number and the original number is 396. What is the original number ?