need help on rounding: does 72.015 round to 72.01 or 72.02?

[mathchic12]

Hey people I need a little help with rounding. I don't know if i should round 72.015 down to 72.01 or up to 72.02. My problem is I forget if you round up or down with 5's at the end and if it changes with decimals. Can anyone help? it's 72.015 degrees north so i am still confused

 

[skeeter]

Re: need help on rounding

rules for rounding

 

[mmm4444bot]

Re: need help on rounding

Hi MathChic:

What do you think you should do? Please tell us.

Think about this number in terms of money: $72.015.

Do you realize that the digit 5 means "half a penny"?

If I OWED you $72.015, then would you expect me to pay you that half a penny, or could I just forget about it, instead?

I cannot cut a penny in half in order to pay you the $0.005 part of what I owe, and you would not be able to spend half a penny even if I could cut a penny.

What if I owed you LESS than half a penny?

$72.014
$72.013
$72.012
$72.011

What if I owned you MORE than half a penny?

$72.016
$72.017
$72.018
$72.019

The general rule when rounding is:

1) IF the fractional part is LESS THAN HALF, then forget about it (i.e., dropping it rounds down)

2) IF the fractional part is EXACTLY HALF OR it is MORE THAN HALF, then don't forget about it; consider the fractional part to be a WHOLE part (i.e, round up).

Please let us know if you need more help understanding how to round 72.015.

Cheers,

~ Mark

 

[mmm4444bot]

Re: need help on rounding

... and if it changes with decimals.

The rules of rounding do not depend on whether or not there is a decimal point in the number.

We round numbers according to POSITION.

72015 is no different than 72.015 when it comes to rounding; what IS important is knowing the position for where the rounding occurs, and that comes from the instructions.

Round 72015 to the nearest ten.

Round 72.015 to the nearest hundreth.

Same rules apply for doing each.

~ Mark