Mathematics: Class 3 — Chapter 6: House of Hundreds - I

• Triangular Torans: Counting triangles in rows. A single line of a triangular toran contains $10$ triangles. Multiple lines are grouped to count larger numbers like $250$ ($50$ more than $200$).
• Bangles: Grouped in tens to count up to $280$ ($200$ and $80$ more).
• Toffees: Counting up to $300$ using boxes of $100$ and loose pieces.

Understanding the transition from $298$ to $300$ through sequential addition:

• $298 + 1 = 299$
• $299 + 1 = 300$

Numbers can be written in multiple ways using addition and subtraction sentences:

• Example: $235$
  • Represented as: $2$ bundles of $100$, $3$ bundles of $10$, and $5$ loose matchsticks.
  • Number Sentence 1: $200$ and $35$ more ($200 + 35$)
  • Number Sentence 2: $15$ less than $250$ ($250 - 15$)
• Example: $316$
  • Number Sentence: $300$ and $16$ more ($300 + 16$)

Arvind Dada packs sweets in boxes of $100$ ($H$), $10$ ($T$), and loose packets of $1$ ($O$):

• $211 = 2H + 1T + 1O = 200 + 10 + 1$
• $309 = 3H + 0T + 9O = 300 + 0 + 9$
• $800 = 8H + 0T + 0O = 800$

Using a slider tool to understand how digits change when a number is increased or decreased:

• Increase $285$ by one $\rightarrow 286$
• Increase $147$ by ten $\rightarrow 157$
• Decrease $367$ by $2 \rightarrow 365$
• Decrease $289$ by $10 \rightarrow 279$
• Increase $290$ by $20 \rightarrow 310$

• Locating numbers between $200$ and $260$ (e.g., $216$, $243$, $257$).
• Locating numbers between $320$ and $390$ (e.g., $329$, $332$, $337$, $375$, $387$).

Calculating how far a number is from a benchmark number:

• The distance from $387$ to $400$ is $13$ units ($400 - 387 = 13$).
• Comparing $393$ and $400$ by jumping along the number line to show that $400$ is $7$ units greater than $393$.

• Moving up one floor increases the number by $10$ (e.g., one floor above $105$ is $115$).
• Moving down one floor decreases the number by $10$.
• Moving right by one house increases the number by $1$ (e.g., one house right of $201$ is $202$).
• Moving left by one house decreases the number by $1$.

Identifying the exact grid position of a house number:

• House Number $13$: Floor = $1\text{st}$, Column = $3$
• House Number $106$: Floor = $10\text{th}$, Column = $6$
• House Number $159$: Floor = $15\text{th}$, Column = $9$

A guessing game for numbers between $200$ and $210$ using directional flags:

• If the guess is too low, the flag points to the right (indicating the target number is larger).
• If the guess is too high, the flag points to the left (indicating the target number is smaller).

A word-play activity where you write a number name, count its letters, and write the name of that new number. This process recursively leads to the number Four:

• "Two hundred and thirty five" ($23$ letters) $\rightarrow$ "Twenty-three" ($11$ letters) $\rightarrow$ "Eleven" ($6$ letters) $\rightarrow$ "Six" ($3$ letters) $\rightarrow$ "Three" ($5$ letters) $\rightarrow$ "Five" ($4$ letters) $\rightarrow$ "Four" ($4$ letters).

Finding all numbers between $200$ and $300$ that contain the digit $5$ (e.g., $205, 215, 225, 235, 245, 250, 251, \dots, 259, 265, 275, 285, 295$).

• Compare the hundreds place first: $321 > 231$ because $3$ hundreds are more than $2$ hundreds.
• If the hundreds place is the same, compare the tens place: $290 > 209$ because $9$ tens are more than $0$ tens.
• If both hundreds and tens are the same, compare the ones place: $157 > 153$ because $7$ ones are more than $3$ ones.

Creating numbers using a given set of digits (e.g., $3, 2, 4$):

• Without repetition: $234, 243, 324, 342, 423, 432$. Greatest: $432$ (Red), Smallest: $234$ (Yellow).
• With repetition allowed: Greatest: $444$, Smallest: $222$.

• Smallest to Biggest (Ascending): $99 < 110 < 207 < 389 < 456$
• Biggest to Smallest (Descending): $494 > 376 > 294 > 249 > 67$