Mathematics: Class 3 — Chapter 12: Give and Take

To solve $364 + 52$:

• Represent $364$ as 3 Hundreds, 6 Tens, and 4 Ones.
• Represent $52$ as 5 Tens and 2 Ones.
• Combine the blocks: Regrouping 10 Tens to form 1 Hundred.
• This leaves us with 4 Hundreds, 1 Ten, and 6 Ones, which equals $416$.

Start at $364$ and make jumps of $+10$ and $+1$ to add $52$:

• Five jumps of $+10$: $364 \rightarrow 374 \rightarrow 384 \rightarrow 394 \rightarrow 404 \rightarrow 414$
• Two jumps of $+1$: $414 \rightarrow 415 \rightarrow 416$

To subtract $75$ from $230$:

• Since we cannot take away 5 ones from 0 ones, we regroup 1 Ten into 10 Ones.
• Now we have 2 Hundreds, 2 Tens, and 10 Ones.
• Subtract 5 ones from 10 ones to get 5 ones.

Next, we need to subtract 7 tens from 2 tens:

• Since we cannot subtract 7 tens from 2 tens, we regroup 1 Hundred into 10 Tens.
• Now we have 1 Hundred, 12 Tens, and 5 Ones.
• Subtract 7 tens from 12 tens to get 5 tens.
• We are left with 1 Hundred, 5 Tens, and 5 Ones, which equals $155$.

Before money existed, people used the Barter System to exchange goods based on mutual needs (e.g., exchanging 5 sacks of rice for 10 sacks of vegetables).

Today, we use coins and notes of different denominations (₹10, ₹20, ₹50, ₹100, ₹500) to buy goods.

• Equivalent Values: Different combinations of notes and coins can represent the same value (e.g., five ₹100 notes are equal to one ₹500 note).
• Making Payments: Finding multiple ways to pay for an item (e.g., paying ₹55 using one ₹50 note and one ₹5 coin, or two ₹20 notes, one ₹10 note, and one ₹5 coin).

Estimate sums and differences by rounding to the nearest hundred:

• $156 + 34 \approx 200$
• $505 + 405 \approx 900$
• $500 - 395 \approx 100$

Compare mathematical expressions by analyzing their components:

• $373 + 40 > 373 + 23$ (since $40 > 23$)
• $345 - 45 > 345 - 54$ (subtracting a smaller number leaves a larger result)