Parts Of A Whole Flashcards
(17 cards)
Converting decimal to %
Move decimal point 2 places to the right
% to decimal
Move decimal point to the left
Decimal to fraction
- Put number over 1
- Simplify fraction by finding the right value of 1/1 to multiply
The number of digits after the decimal point equal what in a fraction…
The number of zeroes in the denominator
% to fraction
Remember percentages are part per 100. So put the number over 100. Adjust for any decimals if needed
Efficiency in the face of long division:
- Estimation
- Remembering common conversions
Multiplying by a power of 10 or dividing by a negative power of 10
Move decimal to the right
Dividing by a power of 10 OR multiply by 10 to a negative power
Shift decimal to the left
Multiplying decimals
- Count decimal places
- Ignore them and multiply normally
- Adjust product by inserting decimals that many places to the left
Multiplying large integers by a decimal…
Exp. 5,000,000 x .0003
Can trade decimal places! Or set up as a factored power of 10
(5 x 10^6) (3 x 10^-4) = 15 x 10^2
Dividing decimals…
- Put them in fraction form
- Multiply both numerator and denominator by necessary power of 10
10% of a number can be rewritten exponentially as…
10^-1
What percent of 125 is 25? Use fractional approach
125 x ?/100 = 25
Simplify
5 x ?/4 = 1
16 is 2% of what number? Use fractional form
16 = 2/100 x ?
Reciprocal bc you divide the % in its fractional form
16 x 100 / 2 =800
Percentage change formula
New - old / old
Or
(New / old) - 1
New % of original number formula
New / old
Most efficient way to find a % of a %
- Concert % into fractions
- Multiply across as normal
