How do u decompose 122 and 3 in math

When you decompose a number you are breaking it into units. 122 will have 3 separate units because it has 3 digits. So, it will be broken down into hundreds, tens and ones and will look like this: 100 + 20 + 2. Note that when you add those together you get a total of 122.

Decomposing 3 is more simple because it is a single digit. It will look like this: 3, because all you are representing is the ones unit. However, some instructors will want you to break a single digit into its various addends, so if your instructor is asking you to do this, it will look like this: 3+0=3, 2+1=3, 1+2=3, 0+3=3.