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Give a four-digit odd number which is greater than 9000 and is divisible by 13. When rounded off to 3 significant figures, it is divisible by 4. When rounded of to 2 significant figures, it is divisible by 11 . Fing the number.
一題難題..教到我做有20分
2007-07-29 3:45 pm
回答 (2)
2007-07-29 4:13 pm
✔ 最佳答案
99191.想一d13 ga倍數先
2.第3significant figures 一定係20/40/60/80 先得
3.第2significant figures 今一定要係11倍數
除左9900 就冇 so is 9919
2007-07-29 8:52 pm
First we can think about that When rounded of to 2 significant figures, it is divisible by 11 and it is a four-digit odd number which is greater than 9000
so it must be 9900
Second, When rounded off to 3 significant figures, it is divisible by 4, and the number is 9880 or 9920.
Third, use 9920 to divided into 13,=763.076....... ,so use 13*763( we need odd number, odd*odd=odd).
So the answer is9919
so it must be 9900
Second, When rounded off to 3 significant figures, it is divisible by 4, and the number is 9880 or 9920.
Third, use 9920 to divided into 13,=763.076....... ,so use 13*763( we need odd number, odd*odd=odd).
So the answer is9919
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