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CLASS – 3 SUBJECT – MATHEMATICS CHAPTER - 2 ADDITION • Addition means putting four or more numbers together. • The numbers we add are called addends. • The number which we get after adding is called the sum of numbers. 456 {ADDEND} + 212 {ADDEND} = 668 {SUM} ADDITION OF FOUR DIGIT NUMBERS WITHOUT CARRY OVER First add the ones, then the tens, then add the Hundred, at last add the thousands. For eg.- Add the following 1. Th H T O 4 2 0 5 + 3 1 5 2 7 3 57 2. Th H T O 5 3 4 6 + 2 4 2 1 7 7 6 7 ADDITION OF FOUR DIGIT NUMBERS WITH CARRY OVER If the sum of digits in the ones, tens or hundreds column is more than 9, we regroup the numbers and carry - over to the next column. For eg.- Th H T O 1 1 1 6 4 5 6 + 2 8 6 8 9 3 2 4 PROPERTIES OF ADDITION • Numbers can be added in any order, but the answer remains the same. For eg.- 4 + 5 = 9 5 + 4 = 9 • When zero is added to a number, the answer is the number itself. For e.g. -8 + 0 = 8 WORDPROBLEMS Q.1. A vegetable seller earned Rs 485 on Monday and Rs 649 on Tuesday. How much did he earn on these two days? Sol.1. Earning on Monday = 485 Earning on Tuesday = 649 Earning on the both days = 485 + 649 = 1134 Ans-The vegetable seller earned Rs 1134. Q.2. In a garden, there are 375 roses, 642 marigolds and 142 lilies. How many flowers are there in the garden? Sol.2. Roses in the garden = 375 Marigolds in the garden = 642 Lilies in the garden = 142 Total flowers in the garden = 375+642+142 =1159 Ans -There are 1159 flowers in the garden. CHAPTER-3 SUBTRACTION Subtraction facts * Subtraction -Subtraction is taking away one number from another number. * Difference - The result of a subtraction problem. * Regrouping - To change Hundreds into Tens and Tens into Ones. Subtraction without borrowing: Example - Subtract 2035 from 9387 Step 1- Subtract the ones Th H T O 9 3 8 7 -2 0 3 5 2 Step 2 - Subtract the tens Th H T O 9 3 8 7 - 2 0 3 5 5 2 Step 3 - Subtract the hundreds Th H T O 9 3 8 7 - 2 0 3 5 3 5 2 Step 4 - Subtract the thousands Th H T O 9 3 8 7 -2 0 3 5 ___________ 7 3 5 2 Thus 9387 - 2035 = 7352 Subtraction with borrowing - Ex. Subtract 5864 from 7652 Th H T O 6 15 14 12 7 6 5 2 -5 8 6 4 ____________ 1 7 8 8 Ans. 1788 Properties of subtraction 1. When a number is subtracted from itself, the difference is 0. e.g. 15 - 15 = 0 2. When 0 is subtracted from a number, the difference is the number itself. e.g. 20 - 0 = 20 Checking of subtraction sums: To check any subtraction sum, add the difference to the smaller number. You Should get the bigger number as the answer. Example: Subtract 5724 from 7656 and check: Checking Th H T O Th H T O 6 16 1 9 3 2 7 6 5 6 -5 7 2 4 ___________ 1 9 3 2 Addition and Subtraction together - +5 7 2 4 ____________ 7 6 5 6 If addition and subtraction are given together, we always add first and Then subtract: Example: Solve 3210 + 1540 – 1580 Solution – By using BODMAS rule Step 1 (Addition) Th H T O 3 2 1 0 + 1 5 4 0 __________ 4 7 5 0 Step 2 (Subtraction) Th H T O 1 4 7 5 0 -1 5 8 0 ___________ 3 1 7 0 Ans: 3170 Word Problem: Q.1. Jamnalal a fruit seller had 560 Kg of apples. He sold 385 Kg during the day. How many apples are left with him? Sol 1 Apples with Jamnalal = 560 Kg Apples sold during the day = 385 Kg Apples left with him = 560 – 385 = 175 Ans- Jamnalal has 175 Kgs left. Q.2. How much should be subtracted from the largest four digit number to get the smallest four digit number? Sol2 – The largest four digit number = 9999 The smallest four digit number = 1000 Difference 9999-1000 = 8999 = Ans- 8999 should be subtracted. Mental Maths 1. The difference between the smallest and the greatest 3 digit number Is? 2. If 13 are subtracted from a number it gives 50, Find the number. 3. The difference between 1000 and 1001 is? 4. 10 less than 365 is 5. 8000 + 2000 - 5000 = 6. 1225 - _____ = 1225 7. 16 – 0 = 8. 1008 - 8 = 9. 2569 - ______= 0 10. 1000 - 999 = ________