consecutive integers ! confused

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consecutive integers ! confused

by charmaine » Sun Aug 03, 2008 4:37 pm
i do not know how the answers came about ? can someone explain it to me ? thanks

of the following, which could be the product of four consecutive positive integers?
a.26 b. 52. c. 80. d. 102. e. 120

answer e

which of the following could be the sum of five consecutive positive integers?
a. 18. b. 24. c. 35. d. 47. e 56

answer c

thank you
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by ricky » Sun Aug 03, 2008 4:43 pm
Fatorize each : prime factorization


120= 2*4*3*5

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by parallel_chase » Sun Aug 03, 2008 11:38 pm
Ques 1.

26=13*2
52=13*2*2
80=5*2*8
102=2*3*17
120=2*3*4*5

Hence E

Ques 2.

a. 18. b. 24. c. 35. d. 47. e 56

1+2+3+4+5 = 15
3+4+5+6+7 = 25
5+6+7+8+9 = 35

Hence C

You can do both calculations in less than 2 minutes.

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by pepeprepa » Mon Aug 04, 2008 1:47 am
You can also learn the five or 6 first factorials, with that you directly finish the first one question.

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by spanlength » Mon Aug 04, 2008 4:56 am
for the 2 part of the question i have let x be the 3rd number of the 5 consecutive numbers.SO other numbers are (x-2) ,(x-1),(x+1 ),(x+2).
So adding all 5 numbers we hav x-2 + x -1 + x + x+ 1+ x+2 = 5x. So ans is a multiple of 5 i.e 35.

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by charmaine » Tue Aug 05, 2008 7:49 pm
thank u guys :)