Frumtæl

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In rīmcræftum, frumtæl oþþe prīmtæl is tæl þæt hæfþ eallrihte twa dǣleras ābūfan nōwiht: 1 and hit. An tæl þæt nis frumtæl hǣtþ man composit tæl, nymðe þæt tæl 1 5s, þæt is nāhwæðer frum ne composit tæl.

Frumtælscipe is se nama for sēo wyrdnes tō bēonne frumtæl. Frumtalu habbaþ dēoplic weorþ in rīmcræfte.

Sēo æfterfylgung þāra frumtala onginnþ:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113

For þǣm horde ealra frumtala wrītþ man ℙ, blæcbord bald P.

In hringlār, sum dǣl þæs smǣtan algebran, hæfþ þæt word "frumlic lim" syndrig andgiet. Hēr is sum hringlim a frumtæl gif, gif a dǣlþ bc mid b and c hringleomu, þā a dǣlþ c oþþe c. Mid þissum andgiete, se additif forlim sum frumtale is ēac frumtæl. For þǣm þe, gif man besēo hord integerum Z swā hringe, −7 is frumtæl.