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like addition,subtraction does not lend it self to true short cuts. unlike addition, there are no sequences of subtraction for which short cuts may be used. for this reason, only a few simple problems in subtraction can be aided through the use of short-cut methods. two of the best are given here.

subtracting a number from the next highest power of 10

rule: starting from the first given digit,record the difference between the digit and 9. continue number. the units digit of the answer is obtained by subtracting given units digit from 10.

the nearest power of 10 which is greater than a given number is a 1 followed by as many zeros as there are digits in the given number. the nearest power of 10 to a number in the “teens” is therefore 100; the nearest power of 10 to a number in the tens of thousands is 100,000 an so on. the following table will help you with differences required in this short cut. it is recomended that you memorize them until they become second nature

given  digit:             0  1  2  3  4  5  6  7  8  9

different with 9:     9  8  7  6  5  4  3  2  1  0

subtract 762 from 1,000.

one thousand, f course, is the next highest power of 10 to 762. subtract each of the digits fom 9,starting from the first. stop at the units digit. the first two answer digits are therefore

23

subtract the given units digit, 2, from 10 to obtained the units answer digit.         238 answer