Rounding math

•  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