Test: Addition and Subtraction - Year 4 MCQ

The column method is essential for addition because it allows numbers to be aligned by their place values (hundreds, tens, and ones), ensuring that digits are added correctly. This method is particularly effective for multi-digit numbers, helping to avoid errors in computation.

If the sum of a column exceeds 9, you must carry over the excess to the next column. For example, if you add 7 and 5, the total is 12; you write down 2 and carry over 1 to the next column. This ensures the accuracy of the overall sum.

The first step in the decomposition method for subtraction is to break the numbers into their place values. For example, 367 can be broken down into 300, 60, and 7. This helps in visualizing the subtraction more clearly and makes regrouping easier when necessary.

To subtract fractions that have the same denominator, follow these steps:

• Subtract the numerators (the top numbers) of the fractions.
• Keep the denominator (the bottom number) the same.
• Write the result as a new fraction.

For example, if you have 3/5 and 1/5, you subtract 1 from 3 to get 2, keeping the denominator 5. So, 3/5 - 1/5 = 2/5.

When adding fractions that have the same denominator, a common mistake is:

• To add the denominators instead of the numerators.

Here's how to correctly add fractions with the same denominator:

• Keep the denominator the same.
• Add only the numerators together.
• Write the sum over the unchanged denominator.

For example, if you are adding 1/4 and 3/4:

• Keep the denominator 4.
• Add the numerators: 1 + 3 = 4.
• The result is 4/4, which simplifies to 1.

By avoiding the mistake of adding the denominators, you can ensure accurate results.

Estimation before calculation is an effective method to verify the reasonableness of an addition problem. By rounding numbers to the nearest ten or hundred, you can quickly check if the final answer is in the expected range, which helps catch errors early in the process.

When you need to regroup during subtraction, you borrow from the next column. For instance, if you need to subtract 8 from 6, you can't do that directly, so you take 1 from the next column, turning the 6 into 16, which allows you to subtract effectively.

When you add fractions and get an improper fraction, you should convert it into a proper fraction or a mixed number. This makes it easier to understand and use in further calculations.

To convert an improper fraction:

• Divide the numerator by the denominator.
• The whole number part becomes the integer of the mixed number.
• The remainder becomes the new numerator, while the denominator stays the same.

For example, if you have the improper fraction 9/4:

• Divide 9 by 4, which gives you 2 with a remainder of 1.
• So, 9/4 can be written as the mixed number 2 1/4.

This method helps in better understanding and using fractions in various mathematical situations.

The decomposition method for subtraction is particularly useful when dealing with multi-digit numbers that require regrouping. This method breaks down the numbers into place values, making it easier to manage borrowing when necessary, ensuring accurate results.

When adding fractions with the same denominator, the first step is to add the numerators while keeping the denominator unchanged. This straightforward approach ensures that the operation remains simple and direct, making it easy to find the total.

A proper fraction is defined as a fraction where the numerator (the top number) is less than the denominator (the bottom number). In this case, we can evaluate the options:

• 9/8: The numerator (9) is greater than the denominator (8). This is not a proper fraction.
• 7/7: The numerator (7) is equal to the denominator (7). This is not a proper fraction; it is equal to 1.
• 4/5: The numerator (4) is less than the denominator (5). This is a proper fraction.
• 10/9: The numerator (10) is greater than the denominator (9). This is not a proper fraction.

Thus, the only proper fraction among the options is 4/5.

To check if your answer in subtraction is reasonable, you can estimate both numbers before performing the actual subtraction. This allows you to see if the result falls within an expected range, helping to confirm the accuracy of your calculation.

Improper fractions can be represented in different forms. The most common representation is as mixed numbers.
Here's a breakdown:

• A mixed number consists of a whole number and a proper fraction.
• For example, the improper fraction 7/4 can be written as 1 3/4.
• This format makes it easier to understand and use in calculations.

Thus, converting improper fractions to mixed numbers is a useful method.

Carrying is a key technique in addition used to manage multi-digit numbers effectively. When the sum of a column exceeds 9, you carry over the excess to the next column. This technique ensures accurate results and is fundamental in handling larger numbers.

When using the column method for subtraction, the first operation performed is to subtract the ones column. After that, you proceed to the tens and then to the hundreds, ensuring that each step is carried out systematically for accurate results.