Samacheer Kalvi Class 4 Maths Solutions Term 3 Chapter 2 Numbers Exercise 2.6

Tamilnadu Samacheer Kalvi 4th Maths Solutions Term 3 Chapter 2 Numbers Ex 2.6

Add and subtract the following problems using multiples of 10, 100 (Mentally)

Question 1. 745 + 40 = _____
Answer: To add 745 and 40 mentally, we can focus on the tens place. The tens digit in 745 is 4, and in 40, it is also 4. Adding these tens gives us 4 tens + 4 tens = 8 tens. So, the number becomes 785. This mental math approach is helpful for quick calculations.
In simple words: To add 745 and 40 in your head, just add the '4' from the tens place of 745 and the '4' from 40. This makes the tens digit '8'. So, 745 plus 40 equals 785.

🎯 Exam Tip: When adding multiples of 10, focus on the tens digit of the first number and add the tens digit of the multiple of 10 to it, keeping the units digit unchanged.

Question 2. 328 + 30 = _____
Answer: To add 328 and 30 mentally, we consider the tens digits. The tens digit in 328 is 2, and in 30, it is 3. Adding these, 2 tens + 3 tens = 5 tens. This changes the tens digit of 328 to 5, making the sum 358. Mental addition helps in quickly solving problems.
In simple words: For 328 plus 30, add the '2' (from the tens place of 328) and the '3' (from 30). This changes the tens digit to '5'. So the answer is 358.

🎯 Exam Tip: Always make sure to only change the place value that corresponds to the multiple (e.g., tens for multiples of 10, hundreds for multiples of 100).

Question 3. 566 + 20 = _____
Answer: To add 566 and 20 mentally, we look at the tens digits. The tens digit in 566 is 6, and in 20, it is 2. Adding them together gives 6 tens + 2 tens = 8 tens. So, the new number is 586. This quick addition only affects the tens place.
In simple words: To add 566 and 20, add the '6' (from the tens place of 566) and the '2' (from 20). This makes '8' in the tens place. So, 566 plus 20 is 586.

🎯 Exam Tip: Practice adding and subtracting simple tens and hundreds numbers to build mental math speed and accuracy.

Question 4. 475 + 100 = _____
Answer: To add 475 and 100 mentally, we focus on the hundreds digits. The hundreds digit in 475 is 4, and in 100, it is 1. Adding these, 4 hundreds + 1 hundred = 5 hundreds. This changes the hundreds digit of 475 to 5, resulting in 575. This simple addition only affects the hundreds place.
In simple words: For 475 plus 100, add the '4' (from the hundreds place of 475) and the '1' (from 100). This makes '5' in the hundreds place. So, 475 plus 100 is 575.

🎯 Exam Tip: When adding multiples of 100, focus on the hundreds digit of the first number and add the hundreds digit of the multiple of 100 to it, keeping other digits unchanged.

Question 5. 686 + 300 = _____
Answer: To add 686 and 300 mentally, we consider the hundreds digits. The hundreds digit in 686 is 6, and in 300, it is 3. Adding them gives 6 hundreds + 3 hundreds = 9 hundreds. This changes the hundreds digit of 686 to 9, resulting in 986. Mental math helps quickly solve such sums.
In simple words: To add 686 and 300, just add the '6' (from the hundreds place of 686) and the '3' (from 300). This makes '9' in the hundreds place. So, 686 plus 300 is 986.

🎯 Exam Tip: When adding or subtracting, identify the place value that will be affected by the multiple of 10 or 100 to make mental calculations faster.

Question 6. 345 + 600 = _____
Answer: To add 345 and 600 mentally, we look at the hundreds digits. The hundreds digit in 345 is 3, and in 600, it is 6. Adding them gives 3 hundreds + 6 hundreds = 9 hundreds. This changes the hundreds digit of 345 to 9, resulting in 945. It's a quick way to add round numbers.
In simple words: For 345 plus 600, add the '3' (from the hundreds place of 345) and the '6' (from 600). This gives '9' in the hundreds place. So the answer is 945.

🎯 Exam Tip: For mental addition, break down numbers into hundreds, tens, and units. Add the hundreds first, then tens, then units, or vice versa, for easier calculation.

Question 7. 6348 - 10 = _____
Answer: To subtract 10 from 6348 mentally, we subtract 1 from the tens digit. The tens digit in 6348 is 4. Subtracting 1 from it gives 4 tens - 1 ten = 3 tens. This changes the tens digit of 6348 from 4 to 3, resulting in 6338. This helps with quick mental subtractions.
In simple words: To take away 10 from 6348, just subtract '1' from the '4' in the tens place of 6348. This makes it '3'. So, 6348 minus 10 is 6338.

🎯 Exam Tip: When subtracting multiples of 10, mentally adjust only the tens digit of the larger number, leaving other digits unchanged.

Question 8. 541 - 40 = _____
Answer: To subtract 40 from 541 mentally, we subtract 4 from the tens digit. The tens digit in 541 is 4. Subtracting 4 from it gives 4 tens - 4 tens = 0 tens. This changes the tens digit of 541 from 4 to 0, resulting in 501. This is a simple way to do subtraction with multiples of ten.
In simple words: For 541 minus 40, subtract the '4' (from the tens place of 541) by the '4' (from 40). This leaves '0' in the tens place. So, 541 minus 40 is 501.

🎯 Exam Tip: Ensure that when subtracting a larger tens digit from a smaller one, you borrow from the hundreds place correctly if required (though not in this example).

Question 9. 495 - 300 = _____
Answer: To subtract 300 from 495 mentally, we subtract 3 from the hundreds digit. The hundreds digit in 495 is 4. Subtracting 3 from it gives 4 hundreds - 3 hundreds = 1 hundred. This changes the hundreds digit of 495 from 4 to 1, leaving 195. It simplifies large number subtraction.
In simple words: To take away 300 from 495, subtract the '3' (from 300) from the '4' (from the hundreds place of 495). This leaves '1' in the hundreds place. So the answer is 195.

🎯 Exam Tip: When subtracting multiples of 100, mentally adjust only the hundreds digit of the larger number, keeping other digits unchanged.

Question 10. 657 - 500 = _____
Answer: To subtract 500 from 657 mentally, we subtract 5 from the hundreds digit. The hundreds digit in 657 is 6. Subtracting 5 from it gives 6 hundreds - 5 hundreds = 1 hundred. This changes the hundreds digit of 657 from 6 to 1, resulting in 157. This makes subtraction of round numbers simple.
In simple words: To take away 500 from 657, subtract the '5' (from 500) from the '6' (from the hundreds place of 657). This leaves '1' in the hundreds place. So, 657 minus 500 is 157.

🎯 Exam Tip: Mental subtraction helps build number sense and makes everyday calculations much faster.

Question 11. 895 - 500 = _____
Answer: To subtract 500 from 895 mentally, we subtract 5 from the hundreds digit. The hundreds digit in 895 is 8. Subtracting 5 from it gives 8 hundreds - 5 hundreds = 3 hundreds. This changes the hundreds digit of 895 from 8 to 3, giving us 395. This method is good for quick calculations.
In simple words: To take away 500 from 895, subtract the '5' (from 500) from the '8' (from the hundreds place of 895). This leaves '3' in the hundreds place. So, 895 minus 500 is 395.

🎯 Exam Tip: Always double-check your mental math by quickly doing a reverse operation (addition for subtraction, or subtraction for addition).

Question 12. 365 - 300 = _____
Answer: To subtract 300 from 365 mentally, we subtract 3 from the hundreds digit. The hundreds digit in 365 is 3. Subtracting 3 from it gives 3 hundreds - 3 hundreds = 0 hundreds. This means the hundreds digit becomes 0, leaving us with 65. Subtracting a number from itself in a place value makes that place value zero.
In simple words: To take away 300 from 365, subtract the '3' (from 300) from the '3' (from the hundreds place of 365). This leaves '0' in the hundreds place. So, 365 minus 300 is 65.

🎯 Exam Tip: When the hundreds digit becomes zero after subtraction, remember to keep the remaining tens and units digits as they are.