So we can't tell you the exact number of times Ron Paul was searched, for instance.
The exact number of jobs under threat at the college is not yet known.
Experts say it is impossible to know the exact number because many kidnappings go unreported.
"I can't give you the exact number, but it's a lot more than eight, " he said.
No-one knows the exact number because there is no national firearms register, our correspondent adds.
As a result of the explosion there are dead and wounded, though their exact number is not yet known.
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Under the changes, a census is to establish the exact number of schools, teachers and pupils in the country.
It did not specify the exact number, but said the troops are still experiencing sporadic resistance in the north.
Although he was unable to confirm the exact number, Mr Tully said the 800 figure was "in the ballpark".
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Of the roughly 120 known elements (the exact number remains a work in progress), about three-quarters were identified by Europeans.
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The exact number of total furloughs planned is still unavailable, since agencies are still deciding how to spread the cuts.
The report also said there are a number of casualties in the action, but the exact number is not yet known.
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It is difficult to determine an exact number because of a lag time in official counts and differences in the states' standards.
More than 250 people are employed at the site but Seven Seas is yet to disclose the exact number of job losses.
The Pentagon said that the exact number of American troops that will be part of the larger contingent has not been determined.
There are various estimates on the exact number of poor in India.
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Obesity is firmly in second place--although the exact number of deaths caused by being overweight is currently the subject of a fierce debate.
Officials anticipate multiple missions will be required to satisfy the test program objectives, but the exact number of missions has not been determined.
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The Department of Health has not published the exact number, but up to 12 children were hospitalised in the three years between 2007 and 2010.
While no one knows the exact number of Microsoft millionaires, Seattle economist Richard Conway has estimated that approximately 10, 000 were created by the year 2000.
While the exact number of these activists is unknown, Mr Loi revealed that his organisation is running at least 400 online accounts and 20 microblogs.
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The exact number may never be established: after the first Gulf war, unreliable estimates were obtained by extrapolating from the number of destroyed Iraqi vehicles.
The exact number of cuts has not been announced thus far.
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He has owned over 5% of Hermes International since 1996, though the exact number of shares he owned had not been disclosed until earlier this year.
The exact number to be moved to a forest sanctuary in Madhya Pradesh - which is more rural - will be determined at a later date.
But there are various estimates of the exact number of poor in India and one suggests that the true figure could be as high as 77%.
The company said the exact number of turbines at the development would depend on which model was selected and numbers will range between 64 and 125.
The education spokesperson raised her concerns over the costs of these mergers and also called for clarity on the exact number of planned university mergers across Wales.
The officer, Superintendent Daniel Musau, said the exact number of people killed could not be established immediately, because some bodies were still trapped in the burnt out buses.
And the exact number is important -- 4, 475 fallen angels.
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