Find the greatest possible length of a rope which can be used to measure exactly the lengths 7m, 3m 85cm and 12m 95cm.

Answer 1

First turn them all into cm: 70cm, 385cm, and 1295cm.
Then find the Greatest Common Factor (the largest number all three numbers as indicated above can divide through evenly with out a decimal). In this case the number is 35.

Answer 2

GCF =5