Two important things when working with percentages are:

•  

Converting between Percentages, Decimals and Fractions

Fractions , Decimals & Percentages

Fraction to decimal Divide

Fraction to percentage

Divide then multiply by 100

Percentage to decimal 

Divide by 100

Percentage to fraction

Change to decimal then use place value principles

Decimal to percentage

Multiply by 100 0.7250.725×100=72.5%

Decimal to fraction Use place value principles.

Percentage Decimal Fraction

82%

0.45

0.375

Percentage Decimal Fraction

82% 82÷100=0.82

45% 0.45

41 5÷12=0.41666….

37.5% 0.375

Find a % of a Quantity• Mrs Higgins makes chocolate chip cookies.  She adds 0.6kg of chocolate chips to a batch.  Little Jack Horner thinks the cookies are too chocolaty… so mrs Higgins only puts 70% of the original amount in.  What weight of chips does she remove?

• Jackie swims lengths.  58 lengths is her max in a day’s training.  Today she only does 85% of her maximum.  How many lengths did she do today?

• Last week, Jackie did 47 lengths.  What percentage of her maximum did she do last week?

• Mr Higgins normally adds 800grams of choc chips to his cookies.  Today he only added 695g.  What percentage of the normal amount did he add to his mixture today?

• Kimberly bought a TV at a sale, 15% off the original price. If the original price was $1450 what was the amount taken off and what was the sale price?

• Find 15% of $1450:– Change 15% to a decimal– 0.15×1450 = $217.50 (=amount taken off

original price)– Sale price = $1450 - $217.50 = $1232.50– The sale price was $1232.50