DOUBLING AND HALVING

                                    DOUBLING

Doubling and halving are very easy to do and can be used to quickly do many simple calculations. Adding two of the same number is called doubling. It comes under the Proportionately formula of Vedic Mathematics. 

For example to double 34 you can find 34 + 34, which is 68. It is the same as multiplying 34 by 2. 34 + 34 = 2 × 34 or 34 × 2. So double 42 is 84. Double 35 is 70. And double 26 is 52, because 26 + 26 = 52. 

Practice A Double the following numbers. Just write down the answer. a 24 b 41 c 14 d 45 e 15 f 25 g 36 h 27 i 18 j 29 k 34 l 4

To double 68 we just think of doubling 60 and 8 and then adding. Double 60 is 120, double 8 is 16. And adding 120 and 16 gives 136. To double 680 we double 68 and put ‘0’ on the end: 1360.
 In the following exercise just write down the answers to the sums. 

Practice B Double the following numbers: 

a 58 b 61 c 73 d 65 e 66 f 88 g 76 h 91 i 380

                                    HALVING 

Halving is the opposite of doubling.

Also half of 46 is 23 because you can halve the 4 and the 6 to get 2 and 3. Half of 54 is 27 because 54 is 50 and 4. And halving 50, 4 you get 25, 2, which make 27. Similarly half of 78 = half of 70 + half of 8 = 35 + 4 = 39. 

Practice C Try some, halve these numbers: a 36 b 28 c 52 d 18 e 34 f 86 g 56 h 32 i 62 j 98

                                             SPLITTING NUMBERS 

You can halve longer numbers easily by splitting them up.
 To halve 178 you halve 100, 70 and 8 and add the results. Half of 100 is 50, half of 70 is 35 and half of 8 is 4. So half of 178 is 50 + 35 + 4 = 89.

Practice D  Halve the following numbers. Try to do them in your head. a 164 b 820 c 216 d 152 e 94 f 326 g 234 h 416 i 380 j 256 k 456 l 57