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Dividing in your head
Learn how to divide in your head by splitting the number.
In your book, Maths Mela (Chapter 9), we learn to divide in our heads by splitting the dividend into convenient parts: parts that are easy to divide.
Look at 1248 ÷ 6. Split 1248 into 1200 + 48. We know 1200 ÷ 6 = 200 (because 12 ÷ 6 = 2) and 48 ÷ 6 = 8. Add the two answers: 1248 ÷ 6 = 200 + 8 = 208.
Sometimes it is easier to split by taking away. 1992 is just 8 less than 2000, so 1992 = 2000 − 8. 2000 ÷ 4 = 500 and 8 ÷ 4 = 2. So 1992 ÷ 4 = 500 − 2 = 498. In the same way, 1560 = 1600 − 40, so 1560 ÷ 8 = 200 − 5 = 195.
To divide by 4, we can halve twice, because 4 = 2 × 2. Half of 128 is 64, and half of 64 is 32, so 128 ÷ 4 = 32. To divide by 8, halve three times, because 8 = 2 × 2 × 2. For 168 ÷ 8: half of 168 is 84, half of 84 is 42, half of 42 is 21. So 168 ÷ 8 = 21.
Choose the split that makes the numbers friendly. For 4824 ÷ 24, split 4824 = 4800 + 24: 4800 ÷ 24 = 200 and 24 ÷ 24 = 1, so the answer is 201.
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