Question

lesson 4: write three - digit numbers

• lets represent three - digit numbers using base - ten numerals.

warm - up: how many do you see: blocks
how many do you see and how do you see them?

Explanation:

Step1: Analyze the first block group

• A large square (hundreds place) has \(10\times10 = 100\) blocks. There are 3 large squares: \(3\times100=300\).
• A ten - rod (tens place) has 10 blocks. There are 2 ten - rods: \(2\times10 = 20\).
• Single blocks (ones place): 4 single blocks.
• Total for first group: \(300 + 20+4=324\).

Step2: Analyze the second block group

• Large squares (hundreds place): 3 large squares, so \(3\times100 = 300\).
• Ten - rods (tens place): 2 ten - rods, so \(2\times10=20\).
• Single blocks (ones place): 4 single blocks.
• Total for second group: \(300 + 20 + 4=324\)? Wait, no, wait. Wait, the second group: large squares: 3, ten - rods: 2, single blocks: 4? Wait, no, looking at the second row: the left has 4 single blocks, then 2 ten - rods, then 3 large squares. So \(3\times100+2\times10 + 4=324\)? Wait, no, maybe I miscounted. Wait, the first row: 3 large squares (100 each), 2 ten - rods (10 each), 4 ones. So \(3\times100 + 2\times10+4 = 324\). The second row: 3 large squares, 2 ten - rods, 4 ones? Wait, no, the second row's left has 4 single blocks, then 2 ten - rods, then 3 large squares. So same as first? Wait, no, maybe the third group: 1 large square, 2 ten - rods, 3 + 4 ones? Wait, no, let's re - examine.

Wait, maybe the problem is to count the number of blocks in each group. Let's take the first figure (top row):

• Hundreds place: 3 large squares (\(3\times100 = 300\))
• Tens place: 2 ten - sticks (\(2\times10=20\))
• Ones place: 4 single blocks
• Total: \(300 + 20+4=324\)

Second figure (middle row):

• Hundreds place: 3 large squares (\(3\times100 = 300\))
• Tens place: 2 ten - sticks (\(2\times10 = 20\))
• Ones place: 4 single blocks
• Total: \(300+20 + 4=324\)? Wait, no, the middle row's left has 4 single blocks, then 2 ten - sticks, then 3 large squares. So yes, \(3\times100+2\times10 + 4 = 324\).

Third figure (bottom row):

• Hundreds place: 1 large square (\(1\times100 = 100\))
• Tens place: 2 ten - sticks (\(2\times10=20\))
• Ones place: 3 (the middle ones) + 4 (the right ones)? Wait, no, the bottom row: 1 large square, then 3 single blocks, then 2 ten - sticks, then 4 single blocks. So \(1\times100+2\times10+(3 + 4)=100 + 20+7 = 127\)? Wait, I think I made a mistake earlier. Let's start over.

Correct analysis for the first block set (top row):

• Hundreds place: Each large square is a \(10\times10\) grid, so it has \(100\) blocks. There are 3 large squares. So \(3\times100=300\).
• Tens place: Each vertical rod has 10 blocks. There are 2 vertical rods. So \(2\times10 = 20\).
• Ones place: There are 4 single blocks.
• Total for top row: \(300+20 + 4=324\).

Correct analysis for the second block set (middle row):

• Hundreds place: 3 large squares. So \(3\times100 = 300\).
• Tens place: 2 vertical rods. So \(2\times10=20\).
• Ones place: 4 single blocks (on the left).
• Total for middle row: \(300+20 + 4=324\).

Correct analysis for the third block set (bottom row):

• Hundreds place: 1 large square. So \(1\times100 = 100\).
• Tens place: 2 vertical rods. So \(2\times10 = 20\).
• Ones place: 3 single blocks (middle) + 4 single blocks (right) \(= 7\) single blocks.
• Total for bottom row: \(100+20 + 7=127\).

But maybe the question is just to count the number of blocks in one of the groups, say the top one. Let's assume we are to find the number of blocks in the top block group.

Answer:

The number of blocks in the top (first) block group is \(\boldsymbol{324}\) (calculated as \(3\times100 + 2\times10+4\)).