Question

Wendy found a small jar with pennies and counted them, and then challenged her brother Craig to guess how many pennies she had. She gave him some clues to help out. The number of pennies is between 70 and 100.You can divide the pennies equally into 5 groups.If you divide the pennies into 4 groups, there will be 3 pennies left over.If you divide the pennies into groups of 6 or 9, there will be 5 left over.If you divide the pennies into groups of 10, there will be 5 left over.How many pennies are in the jar?

Answer 1

The answer is 95.

Dividing it by 10 and getting 5 left over shows that the last digit has to end with a 5. That narrows is down to 75, 85 and 95. Then you subtract 3 from all and divide each of them by 4. If there is a remainder then it's not the right answer which means that only 75 and 95 are the options. Then you subtract 5 from both and divide it by 6 or 9. The one that is divisible is the answer.