What is the least common factor of 4 9 12 and 18?

Answer 1

The Least Common Factor (the smallest positive integer that divides into all the numbers without remainder) for any set of numbers is 1.

Did you mean:

Least Common MULTIPLE (the smallest positive integer which is a multiple of all the numbers), which for {4, 9, 12, 18} is 36; or

HIGHEST common factor (the highest positive integer which divides into all the numbers without remainder), which for {4, 9, 12, 18} is 1.

Note: There is NO highest common multiple for a set of numbers as whatever number is said to be their highest common multiple you can multiply by any number to get an even higher common multiple.