krit.club logo

A Trip to Bhopal - Large Number Addition and Subtraction

Grade 4CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Place Value Alignment: When adding or subtracting large numbers, always align digits in their correct columns: Ten-Thousands (T−ThT-Th), Thousands (ThTh), Hundreds (HH), Tens (TT), and Ones (OO). Imagine vertical lines separating each place value to keep the work organized.

•

Addition with Regrouping: If the sum of digits in a column is greater than 99, write the ones digit in the answer space and 'carry over' the tens digit to the next column on the left. Visually, this carried digit is placed at the very top of the neighboring column.

•

Subtraction with Borrowing: If the top digit in a column is smaller than the bottom digit, you must 'borrow' 11 from the column to the left. This 11 becomes 1010 in your current column. Visually, the digit you borrowed from is crossed out and reduced by 11, while the current digit increases by 1010.

•

Estimation and Rounding: To quickly check if an answer is reasonable, round numbers to the nearest 1010 or 100100. For example, if a bus travels 498498 km and then 302302 km, we can round them to 500+300=800500 + 300 = 800 km to get an approximate total.

•

Interpreting Word Problems: In 'A Trip to Bhopal', look for keywords like 'total', 'altogether', or 'sum' to identify addition. Look for 'how much more', 'difference', or 'remaining' to identify subtraction.

•

Zero in Subtraction: When subtracting from a number with zeros (like 1000−4501000 - 450), you must borrow across multiple columns. The middle zeros usually become 99 after the leftmost non-zero digit is reduced.

📐Formulae

Total Students=Students in Group A+Students in Group BTotal \space Students = Students \space in \space Group \space A + Students \space in \space Group \space B

Difference=Larger Number−Smaller NumberDifference = Larger \space Number - Smaller \space Number

Check:Difference+Smaller Number=Larger NumberCheck: Difference + Smaller \space Number = Larger \space Number

Remaining Distance=Total Distance−Distance CoveredRemaining \space Distance = Total \space Distance - Distance \space Covered

Total Cost=Number of People×Ticket PriceTotal \space Cost = Number \space of \space People \times Ticket \space Price

💡Examples

Problem 1:

A group of 214214 students from one school and 189189 students from another school are going to Bhopal. How many students are going in total?

Solution:

Step 1: Write the numbers in columns. 214214 +189+ 189 Step 2: Add the ones column (4+9=134 + 9 = 13). Write 33 and carry 11 to the tens. Step 3: Add the tens column (1+1+8=101 + 1 + 8 = 10). Write 00 and carry 11 to the hundreds. Step 4: Add the hundreds column (1+2+1=41 + 2 + 1 = 4). Total = 403403.

Explanation:

To find the total, we use addition with regrouping (carrying) for both the ones and tens places.

Problem 2:

The distance from the school to Bhopal is 250250 km. If the bus has already covered 135135 km, how much distance is left to travel?

Solution:

Step 1: Write the numbers in columns. 250250 −135- 135 Step 2: Subtract ones. 0<50 < 5, so borrow from 55 in the tens place. 00 becomes 1010 and 55 becomes 44. 10−5=510 - 5 = 5. Step 3: Subtract tens. 4−3=14 - 3 = 1. Step 4: Subtract hundreds. 2−1=12 - 1 = 1. Result = 115115 km.

Explanation:

We use subtraction to find the 'remaining' distance. Since we cannot subtract 55 from 00, we borrow from the tens place.