Mastering Decimal Addition and Subtraction Techniques

This video tutorial introduces a mental math strategy called compensation, which involves adjusting numbers to simplify calculations and then correcting the result. The video provides examples of using compensation with both whole numbers and decimals, demonstrating how this technique can make mental arithmetic easier.

What is the main idea behind using compensation in mental math?

• Changing one number to make the math easier and then adjusting the answer.

• Using a calculator to solve complex problems.

• Ignoring smaller numbers to simplify calculations.

• Rounding all numbers to the nearest ten.

In the example 32 + 14, what number is subtracted from 32 to make the calculation easier?

• 4

• 2

• 6

• 1

After adjusting 32 to 30 in the example 32 + 14, what is the next step?

• Multiply 30 by 14.

• Add 30 and 14.

• Divide 30 by 14.

• Subtract 14 from 30.

How does compensation help in adding and subtracting decimals?

• By ignoring the decimal part of the numbers.

• By changing one of the addends to make the math easier and then adjusting the sum.

• By rounding decimals to the nearest whole number.

• By converting decimals to fractions.

In the example with Jonathan's shopping, what is the first step to simplify the addition of $23.50 and $5.95?

• Subtract 5 cents from $5.95.

• Add 5 cents to $5.95.

• Round $23.50 to $24.

• Subtract 50 cents from $23.50.

After adjusting $5.95 to $6.00, what is the next step in the calculation?

• Subtract $6.00 from $23.50.

• Add $23.50 and $6.00.

• Divide $23.50 by $6.00.

• Multiply $23.50 by $6.00.

What is the final step after adding $23.50 and $6.00 in Jonathan's shopping example?

• Multiply the sum by 2.

• Add 5 cents to the sum.

• Subtract 5 cents from the sum.

• Divide the sum by 2.

In the example of adding $3.47 and $4.35, what adjustment is made to $3.47?

• Subtract 5 cents.

• Add 3 cents.

• Add 5 cents.

• Subtract 3 cents.

After adjusting $3.47 to $3.50, what is the next step in the calculation?

• Subtract $4.35 from $3.50.

• Add $3.50 and $4.35.

• Divide $3.50 by $4.35.

• Multiply $3.50 by $4.35.

What is the final step after adding $3.50 and $4.35 in the second example?

• Divide the sum by 2.

• Add 3 cents to the sum.

• Subtract 3 cents from the sum.

• Multiply the sum by 2.