How do you round 46,491 to the nearest ten-thousand

You look at the place value before that value. You look at the place value on your right and tell yourself if it's 5 and more you round up, if it's 4 and less you stay and the others turn into 0s. Like this: 46,491 rounds to 46,000.

46,491 rounded to the nearest ten thousand is 50,000.

Because 46,491 is closer to 50,000 than it is to 40,000.