Some definitions - note that the "bi-" frequencies are a bit ambiguous:
• Weekly = 1/week, i.e. something is done once every week
• Biweekly = 1/(2 weeks)
• Quarterly = 1/(3 months)
• Semimonthly = 2/month
• Bimonthly = 1/(2 months)
• Annually = 1/year
• Monthly = 1/month
"Biweekly" is sometimes used to mean "twice per week", but I've looked up "semimonthly" and it seems to strictly mean "once per half-month" or "twice per month". So to avoid ambiguity, I'll take "bimonthly" and "biweekly" to mean "once every two months" and "once every two weeks".
Some conversion factors:
• 1 year = 12 months = 52 weeks
1. Weekly for 1 year:
1/week • 52 weeks = 52 times
2. Biweekly for 2 years:
1/(2 weeks) • 104 weeks = 52 times
3. Quarterly for 4 years:
1/(3 months) • 48 months = 16 times
4. Semimonthly for 1 year:
2/month • 12 months = 24 times
5. Bimonthly for 2 years:
1/(2 months) • 24 months = 12 times
6. Annually for 25 years:
1/year • 25 years = 25 times
7. Monthly for 1/2 year:
1/month • 6 months = 6 times
8. Weekly for 1.5 years:
1/week • 78 weeks = 78 times
9. Semimonthly for 2.5 years:
2/month • 30 months = 60 times
