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Addition and Subtraction - Addition of 5 and 6 digit numbers

Grade 4ICSE

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

🔑Concepts

Place Value Alignment: When adding 55-digit and 66-digit numbers, always align the digits vertically according to their place values. Visualize a table with columns labeled Lakhs (LL), Ten-Thousands (TThTTh), Thousands (ThTh), Hundreds (HH), Tens (TT), and Ones (OO). Align the numbers from right to left to ensure the Ones place of each number is in the same column.

Addends and Sum: The individual numbers being added are called 'Addends,' and the total result obtained after addition is called the 'Sum.' In a column-style visual, the addends are placed one above the other, and the sum is written below a horizontal line.

Order of Operations: Addition always starts from the rightmost column (Ones place) and proceeds column by column to the left (OTHThTThLO \rightarrow T \rightarrow H \rightarrow Th \rightarrow TTh \rightarrow L).

Regrouping (Carrying Over): If the sum of the digits in any column is 1010 or greater, you must regroup. Write the digit in the Ones place of that sum at the bottom of the column and 'carry over' the digit in the Tens place to the top of the next column on the left. Visually, these carry-overs are often written as small digits above the next place value column.

Order Property (Commutative): Changing the order of the addends does not change the sum. For example, 1,23,456+2,00,0001,23,456 + 2,00,000 will give the same result as 2,00,000+1,23,4562,00,000 + 1,23,456.

Grouping Property (Associative): When adding three or more numbers, the way you group the addends does not change the sum. This is helpful when adding three 55-digit numbers mentally by grouping easy pairs first.

Identity Property of Zero: Adding 00 to any 55 or 66-digit number results in the number itself. On a place value chart, a 00 in a column means no value is added to that specific position.

📐Formulae

Addend1+Addend2=Sum\text{Addend}_1 + \text{Addend}_2 = \text{Sum}

a+b=b+aa + b = b + a

(a+b)+c=a+(b+c)(a + b) + c = a + (b + c)

x+0=xx + 0 = x

Total=individual parts\text{Total} = \sum \text{individual parts}

💡Examples

Problem 1:

Add 42,51342,513 and 36,27436,274.

Solution:

TThThHTO42513+3627478787\begin{array}{cccccc} & TTh & Th & H & T & O \\ & 4 & 2 & 5 & 1 & 3 \\ + & 3 & 6 & 2 & 7 & 4 \\ \hline & 7 & 8 & 7 & 8 & 7 \\ \hline \end{array}

Explanation:

  1. Start from the Ones column: 3+4=73 + 4 = 7. 2. Move to the Tens column: 1+7=81 + 7 = 8. 3. Move to the Hundreds column: 5+2=75 + 2 = 7. 4. Move to the Thousands column: 2+6=82 + 6 = 8. 5. Move to the Ten-Thousands column: 4+3=74 + 3 = 7. The final sum is 78,78778,787.

Problem 2:

Add 5,68,9425,68,942 and 2,45,3182,45,318.

Solution:

Step 1: Ones place: 2+8=102 + 8 = 10. Write 00, carry 11 to Tens column. Step 2: Tens place: 1 (carry)+4+1=61 \text{ (carry)} + 4 + 1 = 6. Step 3: Hundreds place: 9+3=129 + 3 = 12. Write 22, carry 11 to Thousands column. Step 4: Thousands place: 1 (carry)+8+5=141 \text{ (carry)} + 8 + 5 = 14. Write 44, carry 11 to Ten-Thousands column. Step 5: Ten-Thousands place: 1 (carry)+6+4=111 \text{ (carry)} + 6 + 4 = 11. Write 11, carry 11 to Lakhs column. Step 6: Lakhs place: 1 (carry)+5+2=81 \text{ (carry)} + 5 + 2 = 8. Sum = 8,14,2608,14,260.

Explanation:

This example requires regrouping (carrying) in multiple columns. We align the 66-digit numbers in columns and process from right to left, adding the carried-over digit to the sum of the next column.