Quick Seven Times (II)

We are going to combine all the above steps into a single step, keeping the logic discussed in detail in the previous article. The only precaution we need to take is while adding half of the neighbor to the double of the digit. When we add half of the neighbor we must check the left-digit of the neighbor. If this one is EVEN then no extra work is required. If that digit is ODD however, you must remember to add 5 more to half of the neighbor! If you want, you can write beforehand 5 on top of a digit if its left hand digit is an odd one! With practice, you might skip this step of noting down 5 to work out seven times of any number in a single step!

We begin by writing ten times of 476 as *4760. The * is added just to make the last calculations easier.

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Now try one more problem of a slightly difficult nature. Find out seven times 3751 independently. Remember that all the digits are odd and you have to take the precaution of adding 5 as per the observation made in the earlier case. Check your mental work and answer with the one given below.

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Go through the procedure two/three times to understand when the adjustment of 5 should be made and how to take in account of the carry. Note that we deal with two digits at a time. One is the digit which we double and the second digit is the one of which we find half. If the digit which we double is an odd one, we have to add 5 along with half of the digit right to the one we are doubling. We add carry, if the number we are doubling has any dot/s noted nearby, which is the result of an earlier calculation.

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