# How can you measure nine minutes with have two hourglasses, one four minute and one seven minute?

Riddle: How can you measure nine minutes with have two hourglasses, one four minute and one seven minute?

This riddle can seem very confusing and difficult. However, if you are careful, you may find a logical answer to this riddle. Let me explain the answer clearly. Turn over both hourglasses at once. When the four-minute hourglass runs out, turn it over.

When the seven-minute hourglass runs out, turn it over. When the four-minute timer runs out this time (eight minutes have elapsed), the seven-minute hourglass has been running for one minute. Now turn over the seven minute timer back over. When the timer runs out, nine minutes have elapsed.

The answer is :  Turn over both hourglasses at once. When the four-minute hourglass runs out, turn it over. When the seven-minute hourglass runs out, turn it over. When the four-minute timer runs out this time (eight minutes have elapsed), the seven-minute hourglass has been running for one minute. Now turn over the seven minute timer back over. When the timer runs out, nine minutes have elapsed.