Please note, that the calculations here is assuming that you purchase the bulk sms units at 1.89 per unit (which as at the time of writing this article, is the price, if you are buying the lowest quantity of sms units at CheapGlobalSMS.com )
Please note that price is not strictly #1.89 per unit (if you are buying greater units, the price per unit reduces accordingly).
See the price list at https://cheapglobalsms.com/price_list
That said; Now, to some networks (e.g the gsm networks of Nigeria; Mtn, etisalat, airtel and glo) sending one page of sms from cheapglobalsms.com requires 1 unit.
I.E; at 1.89 naira per unit,
1sms =1 x 1.89 = 1.89 NGN
Meanwhile, to some countries/networks, it may require more than 1 unit to send a page of Sms.
(see the sms units for each network at https://cheapglobalsms.com/coverage_list )
E.g: if sending 1 page of sms to networks in the United States costs 2 units, this implies:
1sms = 2 x 1.89 = 3.78 NGN