How many 4-digit numbers are multiples of at least one of these two numbers: 2; 5.

There are 5400 4 digit numbers with these two numbers.

Step-by-step explanation:

To get this, you have to find the number of multiples of 2, which is 9000 4 digit numbers, which is 4500, and for 5, it would be 9000/5 = 1800.

So we have 4500 and 1800.

We first have to figure out the union of these two sets (the numbers listed in the two sets with no repeating numbers.

So to do this, we need to figure out how many 4 digit numbers for 10 because that is the repeat which is 2 times 5 = 10.

Now, we divide the 9000 4-digit numbers by 10 to get 900

Finally, we add the 4500, and 1800, and subtract the repeating part, which is 900

This makes the expression 4500+1800-900, which simplifies to 5400.