Counting Numbers that are Multiples of 3 or 5 from 1 to 20
To find out how many numbers from 1 to 20 are either multiples of 3 or 5, we need to identify the numbers that satisfy either condition.

Multiples of 3:
- Multiples of 3 in the range from 1 to 20 are 3, 6, 9, 12, 15, and 18.
- There are a total of 6 numbers that are multiples of 3 in the given range.

Multiples of 5:
- Multiples of 5 in the range from 1 to 20 are 5, 10, and 15.
- There are a total of 3 numbers that are multiples of 5 in the given range.

Numbers that are Either Multiple of 3 or 5:
- To find the numbers that are either multiples of 3 or 5, we need to consider the numbers that are multiples of both 3 and 5, which is 15.
- So, we count 15 only once as it satisfies both conditions.

Total Count:
- Adding the counts of multiples of 3 and 5, we get 6 + 3 = 9.
- However, we need to subtract the common multiple of 15 to avoid double counting.
- Therefore, the total count of numbers that are either multiples of 3 or 5 in the range from 1 to 20 is 9 - 1 = 8.
In conclusion, there are 8 numbers from 1 to 20 that are either multiples of 3 or 5.