Whole numbers have no decimal numbers after them, so your two choices are 4 or 5. When rounding, decimals below 5 round down and those above 5 round up, so your answer should be 4.
421 rounded to nearest tens is 420
420
Oh, what a happy little question! To make 6.421 into the nearest whole number, we look at the decimal part, which is .421. Since .421 is closer to .0 than .1, we round 6.421 down to 6. Happy rounding, my friend!
400
It is 400 rounded to the nearest hundred.
421 rounded to nearest tens is 420
420
420
400
400
42.1
Oh, what a happy little question! To make 6.421 into the nearest whole number, we look at the decimal part, which is .421. Since .421 is closer to .0 than .1, we round 6.421 down to 6. Happy rounding, my friend!
400
It is 400 rounded to the nearest hundred.
Any multiple of 421
420
420