Decoding Decimal Addition and Subtraction

Why is it important to line up decimal points when adding or subtracting decimals?

• To ensure the correct placement of decimal points in the answer

• To make the calculation faster

• To make the numbers look neat

• To avoid using a calculator

What should you do when adding two negative decimal numbers?

• Subtract the values and keep the sign negative

• Add the values and keep the sign positive

• Add the values and keep the sign negative

• Subtract the values and keep the sign positive

In the example -2.3 + -4.5, what is the final answer?

• 2.2

• -6.8

• 6.8

• -2.2

When adding a positive and a negative decimal, what is the first step?

• Add the values directly

• Subtract the values and use the sign of the larger value

• Convert both numbers to positive

• Ignore the signs and add the values

In the example 2.3 + -4.5, what is the final answer?

• -6.8

• 6.8

• -2.2

• 2.2

What is the goal when dealing with subtraction problems involving decimals?

• To divide the values

• To ignore the decimal points

• To multiply the values

• To turn them into addition problems

What does the 'K' in the keep-change-opposite method stand for?

• Keep the first number the same

• Keep the decimal points aligned

• Keep the subtraction sign

• Keep the second number the same

In the example -2.4 - 3.2, what is the final answer after applying the keep-change-opposite method?

• -5.6

• 5.6

• -1.2

• 1.2

What is the opposite of a positive number in the keep-change-opposite method?

• A larger positive number

• Zero

• A smaller positive number

• A negative number

In the example -7.8 - -11.9, what is the final answer?

• -19.7

• -4.1

• 4.1

• 19.7