A number preceded by a plus sign in a telephone number is the country code. In the specific case of +65, that's Singapore.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, and many other countries use different prefixes.)
a number plus 65
65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 + 65 = 65 x 12 = 780
70
A Singapore phone number typically follows the format of 65 XXXX XXXX, with the country code 65 followed by an 8-digit local number.
30 and 41
A Singapore phone number typically follows the format of 65 XXXX XXXX, with the country code 65 followed by an 8-digit local number.
35
The mean value of 100, 70, 70, and 20 is 65
65 + n = 310Subtract 65 from each side of the equation:n = 245
+65 6507 3000
The phone number for contacting businesses in Singapore is typically a local number starting with the country code 65.
65+65=130