ACT Prep Math

Front

What is the formula to calculate a percentage of a number?

Back

To calculate a percentage of a number, use the formula: \( \text{Percentage} = \frac{\text{Part}}{\text{Whole}} \times 100 \) or \( \text{Part} = \text{Percentage} \times \text{Whole} \div 100 \).

Front

How do you calculate 5% of a number?

Back

To calculate 5% of a number, multiply the number by 0.05. For example, 5% of 50 is \( 50 \times 0.05 = 2.5 \).

Front

What is the process to find the total cost after discounts?

Back

To find the total cost after discounts, first calculate the discount amount by multiplying the original price by the discount rate, then subtract the discount from the original price.

Front

How do you calculate the new average monthly bill after a percentage reduction?

Back

To calculate the new average monthly bill after a percentage reduction, multiply the original bill by the percentage reduction (as a decimal) and subtract that from the original bill. For example, a 20% reduction on a $110 bill results in a new bill of \( 110 - (110 \times 0.20) = 88 \).

Front

What is the formula to calculate take-home pay after deductions?

Back

To calculate take-home pay, subtract the total deductions from the gross pay. The formula is: \( \text{Take-home Pay} = \text{Gross Pay} - \text{Deductions} \).

Front

What does it mean to find an equivalent expression?

Back

Finding an equivalent expression means rewriting an expression in a different form that has the same value. For example, \( 80\% \text{ of } n \) can be expressed as \( 0.80n \) or \( \frac{4n}{5} \).

Front

How do you express a percentage as a fraction?

Back

To express a percentage as a fraction, divide the percentage by 100 and simplify if possible. For example, 80% can be expressed as \( \frac{80}{100} = \frac{4}{5} \).

Front

What is the relationship between percentages and decimals?

Back

Percentages can be converted to decimals by dividing by 100. For example, 25% is equivalent to 0.25.

Front

How do you calculate the total cost of multiple items with different discounts?

Back

To calculate the total cost of multiple items with different discounts, calculate the discounted price for each item separately and then sum the discounted prices.

Front

What is the formula for calculating the percentage of a total?

Back

The formula for calculating the percentage of a total is: \( \text{Percentage} = \frac{\text{Part}}{\text{Total}} \times 100 \).