Maysa's error lies in her subtraction of 2.46 from 3.5. Let's break down the correct calculation:
When we correctly perform the subtraction:
\[ 3.50
- 2.46 \]
We can align the numbers based on their decimal points:
3.50
- 2.46
Starting from the rightmost column (the hundredths place):
- In the hundredths place, we have 0 - 6. Since you cannot subtract 6 from 0, we need to borrow from the tenths place. We take 1 from the 5 (in the tenths place), turning it into 4, and the 0 becomes 10 (it's important to note that we effectively have 10 hundredths now).
Now, we can subtract:
- 10 - 6 = 4 (in the hundredths place)
- Now we move to the tenths place: 4 - 4 = 0
- Finally, in the ones place: 3 - 2 = 1
So, the correct answer is:
\[ 3.50 - 2.46 = 1.04 \]
Maysa's Error: Maysa mistakenly calculated the hundredths or tenths, leading her to arrive at 1.16 instead of the correct answer, 1.04. This might be due to not properly aligning the numbers during subtraction or mishandling of borrowing.
Using a Model or Place-Value Concepts: To help Maysa understand her mistake, we can use a visual model such as base ten blocks or a number line.
-
Base Ten Blocks: Demonstrate place value using blocks – show Maysa 3 whole blocks for 3.0 and then create additional tenths and hundredths using smaller blocks. For instance, clearly differentiate between the tenths and hundredths by grouping them appropriately.
-
Number Line: Draw a number line from 0 to 3.5 to visualize the subtraction. Place 3.5 on the number line, then visually find 2.46 by counting back and noting the amount left. Show that when you count back 2.46 from 3.5, you do indeed end up at 1.04.
-
Place Value Charts: Use a place value chart to write down 3.5 and 2.46 distinctly. Clearly show how many ones, tenths, and hundredths each number has, and visually represent step-by-step borrowing.
This way, Maysa can see where the borrowing affects each place value, reinforcing the importance of proper alignment and subtraction.
Thus, the correct answer to the problem, as we clarified, is:
\[ 3.50 - 2.46 = 1.04 \]
1 answer