What number goes into the numbers 140 and 350?

The factors of 140 are:

1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 70, 140

The factors of 350 are:

1, 2, 5, 7, 10, 14, 25, 35, 50, 70, 175, 350

The common factors are:

1, 2, 5, 7, 10, 14, 35, 70