The number 2,874,992 how to round this number to the nearest 10,000

The answer is 2,875,000 because the 4 (in the thousand) is closer to "5"

2,870,000

OK. Take a look at the number just to the right of the digit you want to round to. Since your number is 2,874,992 the digit in the 10,000th place is 7. The digit just to the right of that digit is 4. Now ask yourself ... Is that digit less than 5? If it is, then replace that digit and all the other digits to the right with 0, so you get

2,870,000

as the properly rounded result.

Now let's make a minor change to show rounding up. If you were given the number 2,875,992 then instead of a 4, you would have 5 as the digit just to the right of the 7. And the answer to the question "Is that digit less than 5?" would be no. In which case you still replace that digit and all the others to the right with 0, but you'll also add 1 to the digit you're rounding, getting

2,880,000

But for this problem, the properly rounded result is 2,870,000