Natural number
75 (seventy-five) is thenatural number following74 and preceding76.
75 is aself number because there is no integer that added up to its own digits adds up to 75.[1] It is the sum of the first fivepentagonal numbers, and therefore apentagonal pyramidal number, as well as anonagonal number.[2][3]
It is also the fourthordered Bell number, and aKeith number, because it recurs in aFibonacci-like sequence started from itsbase 10 digits:7,5,12,17,29,46, 75...[4]
75 is the count of the number ofweak orderings on a set of four items.[5]
Excluding theinfinite sets, there are 75uniform polyhedra in the third dimension, which incorporatestar polyhedra as well. Inclusive of 7 families ofprisms andantiprisms, there are also 75uniform compound polyhedra.
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400 to 999 |
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| 400s, 500s, and 600s | 700s, 800s, and 900s | | |
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1000s and 10,000s |
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| 10,000s | |
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100,000s to 10,000,000,000,000s |
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- 100,000
- 1,000,000
- 10,000,000
- 100,000,000
- 1,000,000,000
- 10,000,000,000
- 100,000,000,000
- 1,000,000,000,000
- 10,000,000,000,000
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