Chapter 5 - Number Theory and the Real Number System - 5.1 Number Theory: Prime and Composite Numbers - Exercise Set 5.1 - Page 256: 64

The least common multiple of the two numbers is $4,400$.

Factor each number to obtain: $220=22(10)=11(2)(5)(2)=11(5)(2)(2) \\400=20(20)=5(4)(5)(4)=5(2)(2)(5)(2)(2)=5(5)(2)(2)(2)(2)$ Thus, the least common multiple of the two numbers is $11(5)(5)(2)(2)(2)(2)=4,400$.