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Miscellaneous Elementary Junior High Sum Of Positive Integral Divisors High School |
Subtracting Reverses:A. There are two forms of subtracting reverses and both forms use the same concept. 1. The first form is subtracting a 3 digit number from its reverse. Ex [1] 634 - 436 = __________. 2. The second form is subtracting a 4 digit number but sectioned in pairs, from its reverse. Ex [2] 2314 - 1423 = __________. 3. In both forms take the first number (or first pair) and subtract from the remaining first number (or second pair). 4. The answer follows this form: 100n - n, where n is the result of step 3. Ex [1] 634 - 436 = __________. a. 6 - 4 = 2. b. 100(2) - 2 = 198. c. The answer is 198. Ex [2] 2314 - 1423 = _________. a. 23 - 14 = 9. b. 100(9) - 9 = 891. c. The answer is 891. B. Be careful that the numbers you are subtracting are indeed reverses and also watch out to see if the answer should be negative or positive. C. Another form of reverses is subtracting a 4-digit number from its reverse, but having the same 2 middle digits. 1. To solve these kind of problems use: 1000n - n, where n is the result from subtracting the first digits Ex [3] 4661 - 1664 = ______ a. In this case n = 3, since 4 - 1 = 3. b. The answer is 3000 - 3 = 2997. Ex [4] 3887 - 7883 = ______ a. In this case n = -4, since 3 - 7 = -4. b. The answer is -4000 + 4 = -3996.
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