What is a multiple of 2 and 7?
14 is one. See below for more...
We're looking for Common Multiples - numbers that list both 2 and 7 as factors.
Since both 2 and 7 are prime, there's no need to look at what their factors are - they are 1 and themselves.
And so a quick way to find a multiple of 2 and 7 is to multiply them:
We can now multiply 14 by any number and get another common multiple of 2 and 7. For instance, if we multiply by 10, we get:
In order to arrive at 140, we need both a 2 and 7 in the factor tree, making them common factors.