Walt Rounding

 Rounding

Rounding means making a number simpler but keeping its value close to what it was. The result is less accurate, but easier to use. 

Example: 

73 rounded to the nearest ten is 70, because 73 is closer to 70 than to 80. 

But 76 goes up to 80.

How to Round Numbers

• Decide which is the last digit to keep

• Leave it the same if the next digit is less than 5 (this is called rounding down)

• But increase it by 1 if the next digit is 5 or more (this is called rounding up)

Rounding Decimals

First work out which number will be left when we finish.

• Rounding to tenths means to leave one number after the decimal point.

• Rounding to hundredths means to leave two numbers after the decimal point.

Example

1.2734 rounded to tenths is 1.3   [as the next digit (7) is 5 or more]

3.2416 rounded to hundredths is 3.24  [as the next digit (1) is less than 5]

3.5416 rounded to thousandths is 3.542  [as the next digit (6) is 5 or more]

Exercise 

Question 1

Round these numbers to the nearest ten:

	Number	Nearest Ten
a	62	60
b	346	350
c	451	450
d	673	670
e	7845	7850
f	54	50
g	28	30
h	3694	3690
i	397	400
j	3695	3700

Question 2

Round these numbers to the nearest hundred:

	Number	Nearest Hundred
a	625	600
b	376	400
c	4516	4500
d	3673	3700
e	7845	7800
f	5450	5500
g	2967	3000
h	3954	4000

Question 3

Round these numbers to the nearest thousand:

	Number	Nearest Thousand
a	6254	6000
b	7653	8000
c	4516	5000
d	36734	37000
e	78455	78000
f	59750	60000

Question 4

Round these numbers to the nearest whole number:

	Number	Nearest whole number
a	3.94	4
b	12.14	12
c	23.2	23
d	15.26	15
e	14.52	15
f	90.82	91
g	24.59	25
h	118.4	117

Question 5

Round these numbers to the nearest tenth (1 decimal place):

	Number	Nearest tenths
a	4.83	4.8
b	12.34	12.3
c	23.25	23.3
d	15.26	15.3
e	14.52	14.5
f	90.86	90.9
g	24.59	24.60
h	118.46	118.5

Question 6

Round these numbers to the nearest hundredth (2 decimal places):

	Number	Nearest hundredths
a	1.174	1.17
b	12.346	12.35
c	23.235	23.240
d	15.263	15.26
e	14.528	14.53
f	0.346	0.35
g	0.342	0.34
h	118.467	118.47