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Russian multiplication craig_hunter

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Russian multiplication craig_hunter

1. 1. Russian multiplication Here is how the russians used to multiply. 74 x 45 First write the calculation with the largest number first Half the first number ignore any remainder 37 Double the second number 90 Repeat this process 18 180 9 360 4 720 Stop when the left hand number reaches 1 2 1440 1 2880
2. 2. 74 x 45 The next step is to cross out any even numbers in the left hand column 37 Then cross out opposite numbers in the right hand column 90 18 180 9 360 4 720 2 1440 Russian multiplication 1 2880
3. 3. 74 x 45 Add the remaining numbers in the right hand column 37 90 18 180 9 360 4 720 2 1440 Russian multiplication 1 2880 90 360 2880+ 03 2 3 1 3 Finished 74 x 45 = 3 330
4. 4. 57 x 38 Now try one for yourself, try to keep ahead of the example 28 76 14 152 7 304 3 608 Russian multiplication 1 1216 304 608 1216+ 661 1 2 Finished 57 x 38 = 2 166 2 38
5. 5. Russian multiplication Try these calculations, check your answers with a friend to correct any mistakes 1) 75 x 19 = 2) 79 x 36 = 3) 51 x 29 = 4) 92 x 57 = 5) 47 x 74 = 1425 2904 7479 5244 3478
6. 6. Russian multiplication Try these calculations, check your answers with a friend to correct any mistakes 1) 75 x 19 = 2) 79 x 36 = 3) 51 x 29 = 4) 92 x 57 = 5) 47 x 74 = 1425 2904 7479 5244 3478