Mathletics: Rounding

Rounding

In this class, we will deal with a lot of big or complicated numbers.

Rounding

Rounding is when you take a big or complicated number and make it simpler. Another word for rounding is estimating.

Multiple Choice

Why do we round numbers.

• To make them bigger

• To make them smaller

• To make them have decimals

• To make them simpler

Rounding

We round numbers to a place value. We can round a complicated number like 725.947 to the hundreds place, tens place, ones place, tenths place, or hundredths place. 

What is place value?

A digits place value is its position within a number.

How to Round

• Decide what place value you want to round to.

• Look at the number to the right of the place value.

• If the number to the right is 1-4, you leave the place value alone. If the number is 5-9, you "round up."

• Don't forget to add 0s after the place value all the way to the ones place. 

How to Round

• We are going to round 725.947 to the nearest tens place. The number that is currently in the tens place is 2.

• We look at the number to the right of 2, it is 5.

• Since 5 is in the 5-9 range, we must round up.

• Therefore, 725.947 rounded to the nearest tens place is 730. 

How to Round

• What if we want to round 725.947 to the tenths place?

• What number is currently in the tenths place?

• What number is to the right of the number in the tenths place?
  

• Is the number to the right 1-4? Will you leave the place value alone? Is the number 5-9? Will you round up?

Multiple Choice

What is 725.947 rounded to the tenths place?

• 720

• 730

• 725.9

• 726

Multiple Choice

What is 725.947 rounded to the hundredths place?

• 725.94

• 725.95

• 700

• 800